From Medieval Latin 'musaicum' (work of the Muses) — a sibling of 'museum' and 'music,' all inspired by the Muses.
A picture or pattern produced by arranging small colored pieces of stone, tile, glass, or other materials.
From French 'mosaïque,' from Italian 'mosaico,' from Medieval Latin 'musaicum' or 'musivum' (work of the Muses), from Latin 'musa' (Muse, one of the nine goddesses of art and learning), from Greek 'mousa' (Muse, one who inspires), possibly from PIE *men- (to think, to have in mind) — the Muses being those who put thoughts into artists' minds. The word 'museum' shares the same root (Greek 'mouseion,' place of the Muses). An alternative derivation traces Medieval Latin 'musivum' to Byzantine Greek 'mouseion' specifically denoting mosaic work common in Byzantine
If 'mosaic' truly derives from 'Muse,' then it joins 'museum' (seat of the Muses) and 'music' (art of the Muses) as a third English word honoring the same nine Greek goddesses — making the Muses responsible for art, song, collections, and the painstaking arrangement of tiny colored stones.