Boa, æ, A serpent in Italy, so great and large, that on a time when one was killed, a childe was founde whole in his belly, as Plinie writeth.
Lewis and Short: Latin dictionary
bŏa (also bŏva in the MSS. of Pliny and Festus), ae, f. [bos; cf. boubw/n], a large Italian serpent: in Italiă appellatae bovae in tantam amplitudinem exeuntes ut divo Claudio principe occisae in Vaticano solidus in alvo spectatus infans, Plin. 8, 14, 14, 37; 30, 14, 47, 138 sq.; Sol. 2; acc. to Paul. ex Fest. p. 30 Müll., a water-serpent, so called because it milked cows, Sol. 2, 33; or because it could swallow an ox, quas boas vocant, ab eo quod tam grandes sint ut boves gluttire soleant, Hier. Vit. Hil. Erem. 39.—II.A disease producing red pustules, the measles or small-pox, Plin. 24, 8, 35, 53: boam id est rubentes papulas. id. 26, 11, 73, 120: boas fimum bubulum abolet: unde et nomen traxere, id. 28, 18, 75, 244; Lucil. ap. Fest. s. v. tama, p. 360 Müll.—III. Crurum quoque tumor viae labore collectus bova appellatur, Paul. ex Fest. p. 30 Müll. (the same author explains with these words the disease tama).