wheel hub; nave
Technical term for the central part of a wheel; rarely used in everyday Japanese. The reading こく is an alternative on-reading, but こしき is more common for this character.
The hub is the central part of a wheel where the spokes meet.
Rare kanji for 'wheel hub'; the reading こしき is the primary reading for this character in this meaning.
Kana spelling is more practical for learners and avoids the obscure kanji.
The kanji 轂 is a phono-semantic compound with 車 (vehicle) and 殻 (shell/husk), referring to the hub that encloses the axle. The reading こしき is the native Japanese kun'yomi, while こく is the Sino-Japanese on'yomi.