At

1. A relation of proximity to, or of presence in or on, something; as, at the door; at your shop; at home; at school; at hand; at sea and on land.
2. The relation of some state or condition; as, at war; at peace; at ease; at your service; at fault; at liberty; at risk; at disadvantage.
3. The relation of some employment or action; occupied with; as, at engraving; at husbandry; at play; at work; at meat (eating); except at puns.
4. The relation of a point or position in a series, or of degree, rate, or value; as, with the thermometer at 80°; goods sold at a cheap price; a country estimated at 10,000 square miles; life is short at the longest.
5. The relations of time, age, or order; as, at ten o'clock; at twenty-one; at once; at first.
6. The relations of source, occasion, reason, consequence, or effect; as, at the sight; at this news; merry at anything; at this declaration; at his command; to demand, require, receive, deserve, endure at your hands.
7. Relation of direction toward an object or end; as, look at it; to point at one; to aim at a mark; to throw, strike, shoot, wink, mock, laugh at any one.
At all, At home, At large, At last, At length, At once, etc.
See under All, Home, Large, Last (phrase and syn.), Length, Once, etc.
At it ,
busily or actively engaged.
At least .
See Least and However.
At one .
See At one, in the Vocabulary.