a. Obs. rare. [f. L. ūst-us (see prec.) + -IVE.] a. Caustic. b. Adapted for a burn.
1597. A. M., trans. Guillemeau’s Fr. Chirurg., 22 b/2. Causticke or vstive medicamentes, as Aqva fortis. Ibid. (1592), trans. Gabelhouer’s Bk. Physicke, 332/1. Linteseede-oyle … is an excellent ustive oyntment.
