A formal or technical term for a wisdom tooth. In everyday conversation, 親知らず (oyashirazu) is far more common.
See also: 親知らず
My wisdom tooth is coming in and it hurts.
歯科医に知恵歯の抜歯を勧められた。
The dentist recommended extraction of my wisdom tooth.
Formed from 知恵 “wisdom” and 歯 “tooth,” so called because it erupts at an age traditionally associated with acquiring wisdom.