terra incognita (L.). An unknown country.
tête-à-tête (Fr.). Face to face; in close conversation.
to kalon (Gr.). The beautiful.
toujours prêt (Fr.). Always ready.
tour de force (Fr.). A feat of strength or skill.
tout-à-fait (Fr.). Wholly; entirely.
tout ensemble (Fr.). The whole taken together.
Ubi bene, ibi patria (L.). Where it is well, there is one's country.
Ultima Thule (L.). The utmost boundary or limit.
un fait accompli (Fr.). An accomplished fact.