robust (adj.)youdaoicibaDictYouDict
1540s, from Middle French robuste (14c.) and directly from Latin robustus "strong and hardy," literally "as strong as oak," originally "oaken," from robur, robus "hard timber, strength," also "a special kind of oak," named for its reddish heartwood, from Latin ruber "red" (related to robigo "rust"), from PIE *reudh- (see red (adj.1)). Related: Robustly; robustness. Robustious (1540s) was a common form in 17c. (see "Hamlet" iii.2); it fell from use by mid-18c., but was somewhat revived by mid-19c. antiquarian writers.
stallion (n.)youdaoicibaDictYouDict
mid-15c., earlier staloun (c. 1300), "male horse kept for breeding purposes," from Anglo-French estaloun, Old French estalon "stallion, uncastrated male horse" (Modern French étalon), from Frankish *stal, cognate with Old High German stal "stable," from Proto-Germanic *stalla- (see stall (n.1)). The notion is probably of a horse kept in a stable to service mares. Transferred sense of "robustly lascivious man" is attested from 1550s.