Prosit \Pro"sit\, interj. [L., 3d pers. sing. subj. present of
prodesse to do good; pro for + esse to be.]
Lit., may it do (you) good; -- a salutation used in well
wishing, esp. among Germans, as in drinking healths; -- also
used in the contracted form {prost}.
[Webster 1913 Suppl.]