Plural of bellybutton; the small indented mark on a person's abdomen where the umbilical cord was attached before birth.
From 'belly' and 'button,' combining the stomach area with 'button' (a small rounded object), because the navel resembles a button. This informal term became popular in the 20th century.
Bellybutton is one of those perfectly logical folk words—someone centuries ago looked at a navel and thought 'that looks like a little button' and the name stuck forever!
Complete word intelligence in one call. Free tier — 50 lookups/day.