rarificare

rarificare [ML] , to make (substance) less dense, to rarefy. granum terre commissum ‥ oportet ‥ per ‥ calorem naturalem ~ari [Trevisa: be spradde] et dilatari Bart. Angl. IV 4 p. 92; mutatio frigidi in calidum corpus ~at Gilb. IV 201v. 1; alia medicina ‥ ~at sanguinem cordis Bacon IX 101; quanto plus dominatur siccitas, tanto cum majori difficultate subtiliatur et ~atur ac elucidatur Upton 104.