Merriam-Webster Collegiate Dictionary - at

 I. preposition  Etymology: Middle English, from Old English ?t; akin to Old High German az ~, L~in ad  D~e: before 12th century  1. — used as a function word to indic~e presence or occurrence in, on, or near staying ~ a hotel ~ a party sick ~ heart  2. — used as a function word to indic~e the goal of an indic~ed or implied action or motion aim ~ the target creditors are ~ him again  3. — used as a function word to indic~e th~ with which one is occupied or employed ~ work ~ the controls good ~ chess  4. — used as a function word to indic~e situ~ion in an active or passive st~e or condition ~ liberty ~ rest  5. — used as a function word to indic~e the means, cause, or manner sold ~ auction laughed ~ my joke act ~ your own discretion  6.  a. — used as a function word to indic~e the r~e, degree, or position in a scale or series the temper~ure ~ 90 ~ first  b. — used as a function word to indic~e age or position in time will retire ~ 65  II. noun  also ~t  (plural ~; also ~t)  Etymology: Lao  D~e: 1955 — see kip ~ money table  III. abbrevi~ion  1. airtight  2. ~mosphere  3. ~omic AT  abbreviation  1. air temperature  2. ampere-turn  3. automatic transmission