obrussa
ae, f.
I.
the testing or assaying of gold by fire in a cupel (class.).
I.
Lit.: auri experimentum ignis est: id ipsum obrussam vocant, Plin. 33, 3, 19, § 59: aurum ad obrussam, Suet. Ner. 44.—
II.
Trop., a test, touchstone, proof: adhibenda tamquam obrussa ratio, Cic. Brut. 74, 258: sic verus ille animus probatur: haec ejus obrussa est, Sen. Ep. 13, 1: si omnia argumenta ad obrussam coeperimus exigere, id. Q. N. 4, 5, 1.