At - symb. Chem. the element astatine.

At - unstressed prep.
1 expressing position, exact or approximate (wait at the corner; at the top of the hill; met at Bath; is at school; at a distance).
2 expressing a point in time (see you at three; went at dawn).
3 expressing a point in a scale or range (at boiling-point; at his best).
4 expressing engagement or concern in a state or activity (at war; at work; at odds).
5 expressing a value or rate (sell at Ь10 each).
6 a with or with reference to; in terms of (at a disadvantage; annoyed at losing; good at cricket; play at fighting; sick at heart; came at a run; at short notice; work at it). b by means of (starts at a touch; drank it at a gulp).
7 expressing: a motion towards (arrived at the station; went at them). b aim towards or pursuit of (physically or conceptually) (aim at the target; work at a solution; guess at the truth; laughed at us; has been at the milk again).

at all see ALL . at hand see HAND . at home see HOME . at it 1 engaged in an activity; working hard.
2 colloq. repeating a habitual (usu. disapproved of) activity (found them at it again). at once see ONCE . at that moreover (found one, and a good one at that). at times see TIME . where it's at sl. the fashionable scene or activity. [OE ót, rel. to L ad to]