noun, noun which may take the genitive case particle 'no'
one foot; one leg
Refers to a single foot or leg, often in contexts of balance, injury, or standing on one leg.
彼は片足で立っている。
He is standing on one leg.
片足をけがし
He is practicing standing on one leg.
I injured one leg and can't walk.
one of a pair (of shoes or socks)
Only when written 片足
Used when referring to a single item from a pair, typically shoes or socks. Restricted to the 片足 spelling.
靴下の片足がどこかに行ってしまった。
One of my socks has gone missing.
I injured one of my legs during the soccer match.
The child went outside wearing only one shoe.
両足 refers to both feet or legs together, while 片足 refers to only one of the two.
片膝 uses the 片- prefix with 膝 (knee) to mean one knee, while 片足 uses the same prefix with 足 (leg/foot) to mean one leg, so learners may mix up which body part is meant.
standing on one leg; single-leg stance
Standard kanji spelling; used for both 'one foot/leg' and 'one of a pair' senses.
Alternate kanji spelling emphasizing the leg rather than the foot; less common than 片足.
Compound of 片 (kata, 'one side') + 足 (ashi, 'foot/leg'). The reading かたあし is a straightforward combination of the kun'yomi readings.