Meaning

noun the expensive white fur of the ermine

noun mustelid of northern hemisphere in its white winter coat

originAttested in this form (with s) since at least 1562, in Legh's Accedens of Armorie, which defines it ("Sable poudred with Argent, … Ermines is his proper name") and contrasts it with both ermine and erminois. Related to ermine, but the derivation is unclear; the OED suggests "possibly [from] OF. herminès, pl. of herminet" (a supposed diminutive of hermine); modern French calls the fur…

Etymology from Wiktionary, CC BY-SA 3.0