Uncertain. Often considered to be from the Vulgar Latin root *matteuca, itself from *mattea or mateola + a suffix *-uca, of possibly Gallic origin (compare French massue, Portuguese maça, machuca, Old Portuguese massuca, Italian mazza, mazzocca, Venetian mazuco), or an expressive creation based on the root măc-. Compare also Italian maciulla, Spanish machucar.