Lewis Short
lactesco, ĕre
* V. inch. n. [lacteo]. *
* To turn to milk: omnis fere cibus matrum lactescere incipit,Cic. N. D. 2, 51, 128; Plin. 20, 21, 84, § 230 al.
* To have milk for suckling, to become capable of giving suck: asinae praegnantes continuo lactescunt,Plin. 11, 41, 96, § 237: pectore,Aug. Ep. 150: segetes facit lactescere,to become milky,Serv. Verg. G. 1, 315; v. 2. Lactans.
Charlton T. Lewis, Charles Short, A Latin Dictionary