means A melody is a sequence of musical notes arranged in a satisfying, recognizable line — the part of a song you actually hum.

from From Greek 'melōidia,' a marriage of 'melos' (a song, a tune, a limb of music) and 'aoidē' (singing) — the same 'aoidē' that gives us 'ode.' It traveled through Late Latin 'melodia' and Old French 'melodie' before settling into English. So a melody is, quite literally, a 'song-singing' — the act folded into the thing.