I slipped on the icy road and fell on my backside.
The child fell on his bottom while playing.
first-birthday mochi; mochi for making a baby fall
A traditional custom: a large mochi is tied to a baby's back on or before its first birthday, causing the baby to fall backward (尻餅をつく) as a ritual to ensure healthy growth. This sense is culturally specific and less common in daily conversation.
There is a custom of tying a large mochi to a baby's back on its first birthday.
In this region, they wish for the child's healthy growth by having it step on the first-birthday mochi.
Standard kanji spelling.
Common mixed kana-kanji spelling.
Compound of 尻 (buttocks) and 餅 (mochi). The 'falling' sense comes from the resemblance of landing on one's bottom to a flattened mochi. The 'first-birthday mochi' sense is a literal use of the components.