† ˈustive,a.Obs.rare. [f. L. ūst-us(seeprec.) + -ive.] a. Caustic. b. Adapted for a burn. 1597A. M. tr.Guillemeau's Fr. Chirurg. 22 b/2 Causticke or vstive medicamentes, a Aqva fortis.1599― tr.Gabelhouer's Bk. Physicke 332/1 Linteseede-oyle..is an excellent ustive oyntment.