毛 is the shape of a single strand of animal fur or a bird's feather, curving at the tip — one soft, bent filament. Its core sense is body hair, fur, feather, or down, not the hair of the human head.

Mandarin: máo, 2nd tone. 毛 (máo, fur/hair), 羊毛 (yángmáo, wool), 毛巾 (máojīn, towel), 毛衣 (máoyī, sweater). It is also a colloquial currency unit, one-tenth of a yuan — 一毛钱 (yī máo qián, ten cents). As a surname, 毛泽东 (Máo Zédōng) is the most famous bearer.

Japanese: on-reading モウ (mō), kun け (ke). 毛 (ke, hair), 毛布 (mōfu, blanket), 羊毛 (yōmō, wool), 眉毛 (mayuge, eyebrow). The single syllable け covers hair and fur in general.

Korean hanja-sound "mo": 毛髮 (mobal, hair), 羊毛 (yangmo, wool), 脫毛 (talmo, hair loss), 毛皮 (mopi, fur). A writing brush is 毛筆 (mopil) because it is made of animal hair.

Memory aid: a single filament curving softly at the tip — animal fur, a bird's feather.