the.com/ring finger

means The fourth finger, next to the little finger, traditionally the one on which a wedding or engagement ring is worn.

from The name is just plainly descriptive — the finger where rings are habitually worn. But the habit behind it runs deep: an old European (ultimately Greco-Roman) belief held that a 'vena amoris,' or vein of love, ran directly from this finger to the heart, making it the natural choice for a ring meant to bind two hearts. The vein theory is anatomically false — no such special vein exists — but the custom it inspired outlived the myth, and most Western cultures simply inherited the practice without the explanation.