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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:

Blackstone worked with Morrison to formulate a plan for Jersey Mike’s to offer its first hot Italian sub, which has been a hit.

From The Wall Street Journal Jul. 29, 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

And the other was back in 1986 with West Germany's late sub Pierre Littbarski netting in a quarter-final win over Mexico.

From BBC Jun. 28, 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

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

As the arrested strikers were escorted out of the SUB through doorways near the northwest side of the building, truckloads of New Mexico National Guard soldiers were arriving on the east side of the building.

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

Use the following command: SUB NEW-LIST Your-first-name Your-last-name This is how we usually subscribe to discussion lists.

From The Online World by De Presno, Odd

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

He didn’t stand out in the second half of the season, as Seattle fell from 6-3 to 7-8 before winning the final two games of the regular season, dropping games to the sub-.

From Seattle Times Mar. 6, 2023

Cincinnati does have a very, very long-shot chance for the bye: They would have to beat the Browns and have both Kansas City and Tennessee lose to sub- .500 opponents.

From New York Times Jan. 4, 2022

In "sustain" sus- is a contraction of subs- for sub-.

From New Word-Analysis by William Swinton

"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

Expand that to the present day, including the era of five subs, and there are 10 players who qualify.

From BBC Mar. 27, 2026

“The best way to spot enemy subs is from the sky,” he explained.

From "Hollow City" by Ransom Riggs

"To get subbed in, having not done any efforts in this team, or in this track, or in this order, it was always going to be a bit of a gamble."

From BBC Jul. 30, 2026

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

From The Wall Street Journal Jul. 10, 2026

Somewhere in the mix of all this is Ronaldo, who got the first knockout stage goal of his Cup career with that penalty kick, but also was subbed off late for fresher legs.

From The Wall Street Journal Jul. 3, 2026

The scoring streak started immediately after Hayes subbed back into the game with 7:20 remaining after he scored on his first possession, cutting to the basket for a dunk off an assist from Doncic.

From Los Angeles Times Mar. 4, 2026

I make it through the first four innings of our state tournament game before my not-quite-completely-healed arm is throbbing so bad, I ask to be subbed out.

From "Fast Pitch" by Nic Stone

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

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

Dawson was subbing for Chris Woakes, who will miss the remainder of the match with a shoulder injury sustained on day one.

From BBC Aug. 1, 2025

If there was any good thing that came out of subbing in for that varsity game, it was that Elle and I talked.

From "Here to Stay" by Sara Farizan

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