at

1. expressing location or arrival in a particular place or position.

   they live at Conway House

   they stopped at a small trattoria

2. expressing the time when an event takes place.

   the children go to bed at nine o'clock

   his death came at a time when the movement was split

3. denoting a particular point or level on a scale.

   prices start at £18,500

   driving at 50 mph

4. expressing a particular state or condition.

   his ready smile put her at ease

   they were at a disadvantage

5. expressing the object of a look, thought, action, or plan.

   I looked at my watch

   Leslie pointed at him

   policies aimed at reducing taxation

6. expressing the means by which something is done.

   holding a prison officer at knifepoint

   her pride had taken a beating at his hands

Old English æt, of Germanic origin; related to Old Frisian et and Old Norse at, from an Indo-European root shared by Latin ad ‘to’.

noun

a monetary unit of Laos, equal to one hundredth of a kip.

Thai.

prefix

variant spelling of ad- assimilated before t (as in attend, attenuate ).

symbol

the chemical element astatine.

noun, symbol

the chemical element of atomic number 85, a radioactive member of the halogen group. Astatine was first produced by bombarding bismuth with alpha particles, and it occurs in traces in nature as a decay product.

1940s: from Greek astatos ‘unstable’ + -ine⁴.