a.

Noun

abbreviation (countable and uncountable, plural abbreviations)

1. The result of shortening or reducing; abridgment.
2. A shortened or contracted form of a word or phrase used to represent the whole, using omission of letters, and sometimes substitution of letters, or duplication of initial letters to signify plurality, including signs such as +, =, @.
   • Hants is an abbreviation of Hampshire.
3. The process of abbreviating.
4. A notation used in music score to denote a direction, as pp or mf.
5. One or more dashes through the stem of a note, dividing it respectively into quavers, semiquavers, demisemiquavers, or hemidemisemiquavers.
6. Any convenient short form used as a substitution for an understood or inferred whole.
   • The phrase "civil rights" is an abbreviation for a whole complex of relationships.1946-1947, Harry S. Truman, President Truman's committee on Civil Rights

See all 8 meanings of abbreviation

Noun

acceleration (countable and uncountable, plural accelerations)

1. (uncountable) The act of accelerating, or the state of being accelerated; increase of motion or action; as opposed to retardation or deceleration.
   • A falling body moves toward the earth with an acceleration of velocity.
2. (countable) The amount by which a speed or velocity increases (and so a scalar quantity or a vector quantity).
   • The boosters produce an acceleration of 20 metres per second per second.
3. The change of velocity with respect to time (can include deceleration or changing direction).
4. The advancement of students at a rate that places them ahead of where they would be in the regular school curriculum.