| atout | trump |
| ATP | ATP |
| ATPasi fosfolipide-traslocante | Flippase |
| ATR | ATR |
| ATRAC | Adaptive Transform Acoustic Coding |
| Atrani | Atrani |
| Atrazina | Atrazine |
| Atrebati | Atrebates |
| Atreo | Atreus |
| Atridi | Atreidae |
| atrio | atrium |
| Atriplex | Atriplex |
| atroce | heinous |
| Atrociraptor marshalli | Atrociraptor |
| atrocità | cruelty |
| atrofia | atrophy |
| Atrofia multi-sistemica | Multiple system atrophy |
| atrofizzato | atrophied |
| Atromitos | Atromitos |
| Atropa belladonna | Deadly nightshade |
| Atropina | Atropine |
| Atropo | Atropos |
| ATSC | ATSC Standards |
| Atsushi Yanagisawa | Atsushi Yanagisawa |
| attacca | rages |
| attaccabile | assailable |
| attaccabriche | squabblers |
| attaccabrighe | fighter |
| attaccamento | adherence |
| attaccamento al dovere | devotion to duty |
| attaccamento per | attachment |
| attaccante | attacking |
| attaccapanni | coat hanger |
