Laudator Temporis Acti

An auto-antonym is a word that can mean the opposite of itself. Latin obesus is such a word, meaning either fat or thin, although the evidence for thin is meagre.

Lewis and Short, A Latin Dictionary, s.v. obedo (from an online version; I don't have the book):

ŏb-ĕdo, ēdi, ēsum, ĕre, to eat, eat away, devour (used only in the part. perf. and P. a.).—Trop.: nec obesa cavamine terra est, AUCT. AETN. 344.—Hence, P. a.: ŏbēsus, a, um.
I. Wasted away, lean, meagre: corpore pectoreque undique obeso, Laev. ap. GELL. 19, 7, 3; and ap. NON. 361, 17: (obesum hic notavimus proprie magis quam usitate dictum pro exili atque gracilento, Gell. ib.: obesum gracile et exile, Non. l.l.).—
II. Mid., that has eaten itself fat; hence, in gen., fat, stout, plump: obesus pinguis quasi ob edendum factus, Paul. ex FEST. p. 188 Müll. (not in Cic.; perh. not ante-Aug.; syn.: opimus, pinguis): corpus neque gracile, neque obesum, CELS. 2, 1; cf. COL. 6, 2, 15: turdus, HOR. Ep. 1, 15, 40: sus, COL. 7, 10, 6: terga, VERG. G. 3, 80: cervix, SUET. Ner. 51.—Sup.: obesissimus venter, PLIN. 11, 37, 79, 200; SUET. Vit. 17; APP. M. 11, p. 263.—Poet.: fauces obesae, swollen, VERG. G. 3, 497.

Félix Gaffiot, Le Dictionnaire illustré latin-français, s.v. obesus:

Labels: auto-antonyms