used when mentioning someone or something for the first time in a text or conversation
used with units of measurement to mean one such unit
one single; any
used when mentioning the name of someone not known to the speaker
someone like (the name specified)
used to indicate membership of a class of people or things
in, to, or for each; per (used when expressing rates or ratios)
the first letter of the alphabet.
denoting the first in a set of items, categories, sizes, etc.
denoting the first of two or more hypothetical people or things
the highest class of academic mark
(in the UK) denoting the most important category of road, other than a motorway
denoting the highest-earning socio-economic category for marketing purposes, including top management and senior professional personnel.
denoting the first file from the left, as viewed from White's side of the board.
the first constant to appear in an algebraic expression.
denoting the uppermost soil horizon, especially the topsoil.
the human blood type (in the ABO system) containing the A antigen and lacking the B.
(with numeral) denoting a series of international standard paper sizes each twice the area of the next, as A0, A1, A2, A3, A4, etc., A4 being 210 × 297 mm.
a shape like that of a capital A
the sixth note of the diatonic scale of C major. The A above middle C is usually used as the basis for tuning and in modern music has a standard frequency of 440 Hz.
a key based on a scale with A as its keynote.
