the word sanguine

This is a word that doesn't mean what I thought it did. Maybe if I start posting these, it will help me to remember the actual new-to-me meaning as opposed to (or at least in addition to) the false meaning.

Sanguine (adj.) - cheerfully optimistic, hopeful, or confident.

Sanguine (adj.) - cheerful, hopeful, vivacious, confident

I knew the word "sanguine" derived from a word for "blood", but thought it meant "calm, content, unperturbed". I didn't know why a word based on "blood" would mean any of those things; the actual meaning makes more sense in that regard.