aurum potabile (L.), potable gold.
au second (Fr.), on the second [floor].
au secret (Fr.), in close custody or confinement.
au sérieux (Fr.), seriously.
auspex, pl. auspices (L.), an augur in ancient Rome;—auspicium, pl. auspicia, an observation made by an augur.
auspicium melioris ævi (L.), augury of a better age.
aussitôt dit, aussitôt fait (Fr.), no sooner said than done.
aut amat aut odit mulier, nihil est tertium (L.), a woman either loves or she hates, there is no third course for her.
autant d'hommes (or de têtes), autant d'avis (Fr.), so many men, so many minds.
aut Cæsar aut nullus (L.), either Cæsar or nobody.