Lewis & Short

bŏo (with the digamma bŏvo, Enn.; v. infra), āre or ĕre, v. n. [from the root bo, kindr. with Sanscr. gu and the Gr. βοάω; cf. Varr. L. L. 7, § 104 Müll.; Non. p. 79, 4; acc. to Paul. ex Fest. p. 30 Müll. directly from the Gr.], to cry aloud, roar (mostly ante- and post-class., and in the poets).

      1. a. Bŏvo, āre: clamore bovantes, Enn. ap. Varr. 1. 1. (Ann. v. 571 Vahl.).
      2. b. Bŏo, ĕre: clamore et sonitu colles resonantes bount, Pac. ap. Non. 1. 1. (Trag. Rel. v. 223 Rib.; Varr. ib.; perh. in both pass. we should read boant; cf. Ussing ad Plaut. Am. 1, 1, 77).
      3. c. Bŏo, āre (the usual form): boat Caelum fremitu, Plaut. Am. 1, 1, 77; Ov. A. A. 3, 450; App. Flor. 17.