ustĭo

I. a burning, searing, or cauterizing (post-Aug. and very rare): si costa cariosa est, inutilis ustio, Cels. 8, 2 fin.: quaedam ustione sanantur, Plin. 34, 15, 44, § 151: vehementior sinapis, id. 20, 22, 87, § 239.