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  • sub
    sub
    noun
    a submarine.
  • SUB
    SUB
    abbreviation
    supplemental unemployment benefits.
  • sub-
    sub-
    a prefix occurring originally in loanwords from Latin (subject; subtract; subvert; subsidy ); on this model, freely attached to elements of any origin and used with the meaning “under,” “below,” “beneath” (subalpine; substratum ), “slightly,” “imperfectly,” “nearly” (subcolumnar; subtropical ), “secondary,” “subordinate” (subcommittee; subplot ).
  • sub.
    sub.
    abbreviation
    subordinated.
  • sub–
    sub–
    A prefix that means “underneath or lower” (as in subsoil), “a subordinate or secondary part of something else” (as in subphylum.), or “less than completely” (as in subtropical.)
Synonyms

sub

1 American  
[suhb] / sʌb /

noun

  • subs
    plural
  1. a submarine.

  2. a substitute.

    We've got a sub in English this week because our teacher's home with the flu.

  3. a submarine sandwich.

  4. a submissive in a BDSM sexual encounter or relationship.

  5. a subcontractor.

  6. a sublieutenant.

  7. a subordinate.

  8. a subaltern.

  9. British. an advance against one's wages, especially one granted as a subsistence allowance.

  10. Photography. a substratum.

  11. a subscriber.


verb (used without object)

  • subs,
    present (3rd person singular)
  • subbed,
    past participle,  past
  • subbing
    present participle
  1. to act as a substitute for another.

  2. to act as the submissive partner in a BDSM sexual encounter or relationship.

verb (used with object)

  • subs,
    present (3rd person singular)
  • subbed,
    past participle,  past
  • subbing
    present participle
  1. Photography. to coat (a film or plate) with a substratum.

SUB 2 American  

abbreviation

  1. supplemental unemployment benefits.


sub- 3 American  
  1. a prefix occurring originally in loanwords from Latin (subject; subtract; subvert; subsidy ); on this model, freely attached to elements of any origin and used with the meaning “under,” “below,” “beneath” (subalpine; substratum ), “slightly,” “imperfectly,” “nearly” (subcolumnar; subtropical ), “secondary,” “subordinate” (subcommittee; subplot ).

  2. Chemistry.

    1. a prefix indicating a basic compound.

      subacetate; subcarbonate; subnitrate.

    2. a prefix indicating that the element is present in a relatively small proportion, i.e., in a low oxidation state.

      subchloride; suboxide.


sub. 4 American  

abbreviation

  1. subordinated.

  2. subscription.

  3. substitute.

  4. suburb.

  5. suburban.

  6. subway.


sub- 1 British  

prefix

  1. situated under or beneath

    subterranean

  2. secondary in rank; subordinate

    subeditor

  3. falling short of; less than or imperfectly

    subarctic

    subhuman

  4. forming a subdivision or subordinate part of a whole

    subcommittee

    1. indicating that a compound contains a relatively small proportion of a specified element

      suboxide

    2. indicating that a salt is basic salt

      subacetate

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

sub 2 British  
/ sʌb /

noun

  1. short for several words beginning with sub- See subaltern subeditor submarine subordinate subscription substandard substitute substratum

  2. Formal term: subsistence allowanceinformal an advance payment of wages or salary

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

verb

  1. (intr) to serve as a substitute

  2. informal (intr) to act as a substitute (for)

  3. informal to grant or receive (an advance payment of wages or salary)

  4. informal (tr) short for subedit

  5. (tr) photog to apply a substratum to (a film or plate base)

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
sub. 3 British  

abbreviation

  1. subeditor

  2. subito (in music)

  3. subscription

  4. substitute

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

sub– Scientific  
  1. A prefix that means “underneath or lower” (as in subsoil), “a subordinate or secondary part of something else” (as in subphylum.), or “less than completely” (as in subtropical.)


Regionalisms

See hero sandwich.

Other Word Forms

Inflected Forms

Nouns

Participles

Conjugated Forms

Present

Past

Future

Etymology

Origin of sub1

By shortening of words prefixed with sub-

Origin of sub-3

< Latin, combining form representing sub (preposition); akin to Greek hypó; see hypo-

Explanation

If a history buff mentions a sub, she's probably referring to an underwater warship. But if your friend wants a sub for lunch, he hasn't suddenly developed a taste for warships — he just wants a sandwich. Sub is short for submarine, the cylindrical watercraft with rounded ends that can operate deep beneath the water. Sub can also refer to a long sandwich filled with meat, cheese, and veggies; this kind of sub goes by different names in different parts of the country, including hero, hoagie, and grinder. The sub in your geometry classroom is probably just a substitute teacher.

Keep Reading on Vocabulary.com

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

The Navy has been trying to boost submarine production for years with the goal of building two Virginia-class and one Columbia-class sub each year.

From The Wall Street Journal Aug. 13, 2026

Quantum mechanics is the branch of physics that explains how matter and energy behave at the atomic and sub atomic scale.

From Science Daily Jul. 13, 2026

During the 13-week quarter that ended June 28, that growth stood at 2.3%, the company said, with its popular limited-time chicken salad sub and digital marketing efforts driving the gains.

From MarketWatch Jul. 2, 2026

The sub took up to three people on the dives, collecting the fossil samples using robotic arms.

From Barron's Jun. 10, 2026

“People sub out O for zero when they talk sometimes, right?”

From "The Darkest Minds" by Alexandra Bracken

Emma Davis helps to run The SUB Lisburn, which opened its doors to parents looking cheaper uniforms in 2021.

From BBC Aug. 28, 2023

From a raised seating area outside the SUB cafeteria, Dressman saw a guardsman running toward him.

From Washington Times May 16, 2020

When they rejoined the sit-in strikers, “maybe 4:30 or 5 p.m., local police officers came in with a restraining order to have the SUB evacuated,” she said.

From Washington Times May 16, 2020

The reality was that he and Darcy didn’t have much cushion, and his SUB pay was about to be cut in half, and his GM health benefits were going to run out.

From Washington Post Apr. 15, 2017

Thus they, in two long rows, 30,000 of them by the tale, dine joyfully SUB DIO.

From History of Friedrich II of Prussia — Volume 07 by Thomas Carlyle

The National Labor Relations Act doesn’t allow sub- and independent contractors to unionize.

From The Wall Street Journal Aug. 12, 2026

Due to its unusual climate, the island is rich in biodiversity, serving as a breeding site for southern elephant and sub- Antarctic fur seals.

From BBC Feb. 12, 2025

Eris “is essentially a sub-, sub-variant of XBB,” according to Pan.

From Los Angeles Times Aug. 10, 2023

This has created the bowl-like shape of the region, which creates an overall internal drainage, and countless sub- drainages in individual basins.

From Textbooks Jan. 1, 2017

The first class is Spanish, all about sub- jects and predicates.

From "The Queen of Water" by Laura Resau

"For Deniz it was clear, he gave us a lot in the last game when he was a sub. Deniz doesn't need to be prepared, he can jump in right away."

From BBC Jun. 21, 2026

A quick run-down: I adore sunchokes but they're notoriously difficult to find at most stores, so if you need to sub. this out for anything, I'd opt for any other root vegetable.

From Salon May 14, 2023

Unperplexed by all the hubbub, Said he: “It’s the guy from Grubhub, Bringing me my favorite pub sub. Just a sandwich, nothing more.”

From Washington Post Aug. 8, 2019

“I want to see the difference in a nuclear-powered sub. For me, it’ll be like going on a Carnival Cruise ship,” he said.

From Washington Times Sep. 29, 2014

“Since this is the first run, we want to go easy on the sub. We’ll head out from shore and go twenty feet down, make a circle and come back.”

From "Wolfie & Fly" by Cary Fagan

Philly Cheesesteaks, along with new hot Italian subs, have proven popular among younger consumers.

From MarketWatch Jul. 30, 2026

“I don’t feel comfortable taking him in during a strike with subs who do not know my son’s needs,” Gonzalez said.

From Los Angeles Times Apr. 29, 2026

If the subs have done their jobs but weren’t paid, consider paying them.

From The Wall Street Journal Apr. 25, 2026

Military strategist Eyck Freymann in his new book about defending Taiwan describes subs as “the door-kicker for the rest of the force” in a war with China.

From The Wall Street Journal Apr. 23, 2026

Nuclear-powered subs could have hidden deep underwater for long periods of time—but the navy was still redesigning its nuclear subs.

From "Fallout: Spies, Superbombs, and the Ultimate Cold War Showdown" by Steve Sheinkin

Even there, I tried to work when my kid was subbed out.

From The Wall Street Journal Jul. 10, 2026

After the goal, U.S. star Christian Pulisic was subbed out after sustaining an apparent leg injury while attempting a shot.

From Los Angeles Times Jul. 7, 2026

"It's so tough playing an individual sport. You can't be subbed out, you just have to be dunked back in the deep end immediately," former British player Naomi Broady said on BBC TV.

From BBC Jun. 29, 2026

Under coach Roberto Martinez, he has been subbed off 13 times across the 30 matches he started, but only once before the 60th minute - in the 5-0 win against Armenia in September 2025.

From BBC Jun. 23, 2026

Mr. Cobb sometimes subbed for their Social Studies teacher, and he always managed to slip in a story about the Vietnam War, even when their class unit was on ancient civilizations.

From "Aru Shah and the End of Time" by Roshani Chokshi

Nearing his 126th show, Fedigan has worked his way up the ranks from subbing in as a spotlight operator to overseeing the entire technical production of hit shows like “Chicago.”

From The Wall Street Journal Feb. 27, 2026

It was enough to make Bilodeau’s coach go to his bench, Cronin subbing in Brandon Williams for Bilodeau, who remained on the bench for more than five minutes.

From Los Angeles Times Nov. 8, 2025

Megyn Kelly, however, defended Carlson, arguing on X that “No one is expecting any of the ppl subbing for Charlie to imitate Charlie.”

From Salon Oct. 29, 2025

Importantly, subbing out water for sports drinks is not going to cut it: “It functionally makes very little difference in terms of people’s outcome,” Charlton said.

From Slate Aug. 17, 2025

Mother was still reporting to her empty classroom when she wasn’t subbing, and Daddy had been let go for next year, but he still had to finish out this one.

From "The Lions of Little Rock" by Kristin Levine

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