Old English mawan "to cut (grass, etc.) with a scythe or other sharp instrument" (class VII strong verb; past tense meow, past participle mawen), from Proto-Germanic *mæanan (source also of Middle Low German maeyen, Dutch maaien, Old High German maen, German mähen "to mow," Old English mæd "meadow"), from PIE root *me- (4) "to cut down grass or grain." Related: Mowed; mown; mowing.
"stack of hay," Old English muga, muwa "a heap (of grain, pease, etc.), swath of corn; crowd of people," earlier muha, from Proto-Germanic *mugon (source also of Old Norse mugr "a heap," mostr "crowd"), of uncertain origin. Meaning "place in a barn where hay or sheaves of grain are stored" is by 1755.