tún
buttocks
Phonosemantic compound. ⺼ represents the meaning and 殿 represents the sound. Originally written as 𡱒, which depicted a a person (尸) with their buttocks (𠂤) emphasized.
Evolution

Oracle script
(~1250-1000 BC)
Bronze script
Late Western Zhou (~800 BC)
Seal script
Shuowen (~100 AD)
Clerical script
Eastern Han dynasty (25-220 AD)Regular script
ModernSources