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• Ab
  Ab

  noun

  Av.
• AB
  AB

  abbreviation

  able seaman.
• ab-
  ab-

  a formal element occurring in loanwords from Latin, where it meant “away from”.
• ab.
  ab.

  abbreviation

  about.
• A.B.
  A.B.

  abbreviation

  Bachelor of Arts.

Ab

¹ American  

[ahb, ahv] / ɑb, ɑv /

noun

1. Av.

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Ab ² American  

Symbol.

1. Chemistry. alabamine.

2. Immunology. antibody.

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AB ³ American  

abbreviation

1. Nautical. able seaman.

2. airborne.

3. U.S. Air Force. Airman Basic.

4. Alberta, Canada (approved for postal use).

5. antiballistic; antiballistic missile.

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AB ⁴ American  

Symbol, Physiology.

1. a major blood group usually enabling a person whose blood is of this type to donate blood to persons of type AB and to receive blood from persons of type O, A, B, or AB.

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ab- ⁵ American  

1. a formal element occurring in loanwords from Latin, where it meant “away from”.

   abdicate; abolition.

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ab. ⁶ American  

abbreviation

1. about.

2. Baseball. (times) at bat.

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A.B. ⁷ American  

abbreviation

1. Bachelor of Arts.

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A.B. ⁸ American  

abbreviation

1. Nautical. able seaman.

2. Baseball. (times) at bat. Also a.b.

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AB ¹ British  

abbreviation

1. Also: a.b..  able-bodied seaman

2. (in the US) Bachelor of Arts

3. (esp in postal addresses) Alberta (Canada)

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symbol

1. a human blood type of the ABO group, containing both the A antigen and the B antigen

Ab ² British  

/ æb /

noun

1. a variant of Av

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ab- ³ British  

prefix

1. away from; off; outside of; opposite to

   abnormal

   abaxial

   aboral

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ab- ⁴ British  

prefix

1. denoting a cgs unit of measurement in the electromagnetic system

   abvolt

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Etymology

Origin of ab-⁵

< Latin ab (preposition and prefix) from, away, cognate with Greek apó, Sanskrit ápa, German ab, English of ¹, off

Origin of A.B.⁷

< New Latin, Medieval Latin Artium Baccalaureus

Explanation

An ab is a stomach, or abdominal, muscle. Doing sit ups and crunches will help you tone your abs. Ab is shorthand for abdominal, which comes from the Latin abdomen, "belly," and it's a common name for what's formally known as the rectus abdominus muscle. Your abs run up and down the front of your torso, on either side of your belly button. In extremely fit or muscly people with little body fat, you can actually see how the abs are separated into several sections, the so-called "six-pack."

Example Sentences

The next step will be a larger Phase II clinical trial led by Atrogi AB, the company developing the drug.

From Science Daily • Jun. 3, 2026

Several authors of the study are employed by Atrogi AB and/or own shares in the company, which funded the clinical trial.

From Science Daily • Jun. 3, 2026

AB is a reluctant transgender athlete pioneer who prefers to be known for so much more than just her gender identity, but the prospect of hiding because she was relentlessly attacked didn’t feel right, either.

From Los Angeles Times • Jun. 1, 2026

A petition was launched to convince AB Foods to reverse its decision to end production or allow someone else to continue making it.

From The Wall Street Journal • Jun. 1, 2026

A friend of a friend, a cool AB with tons of money, is writing a book called Traveling While Black.

From "Americanah" by Chimamanda Ngozi Adichie