The first letter of the English alphabet, called a and written in the Latin script.

The ordinal number first, derived from this letter of the English alphabet, called a and written in the Latin script.

A rank, normally the highest rank, on any of various scales that assign letters. / (education) The highest letter grade assigned (disregarding plusses and minuses).

Ace. (including in card games) / Acre. / Adult; as used in film rating. / Ammeter. / (physics) Angstrom. / Answer. / (sports) An assist. / (sexuality) Asexual. / (UK, London) Arsehole. / (weaponry) Atom.

(weaponry) Atom; atomic.

(non-productive) From. / (non-productive) Away from; outside of.

(physics) A unit of electromagnetic charge in the centimeter-gram-second system: the abcoulomb.

(historical) A Dutch and German measure of liquids, used in England for Rhine wine, varying in different cities, being in Amsterdam about 41 wine gallons, in Antwerp 36½, and in Hamburg 38¼.

The dignity, estate, term, or jurisdiction of an abbot or abbess.

A means of defense formed by felled trees, or sometimes by bent trees, the ends of whose branches are sharpened and directed outwards, or against the enemy, and more recently fortified with barbed wire.