The Chinese character ? looks a bit like a mouth full of teeth, which is appropriate since the meaning of this character is teeth.

The original form of this character was a U-shaped mouth with six teeth, which were reduced to four as the character evolved. The simplified version (?) has just one tooth – a fact which can be remembered by associating old age with tooth loss.

The radical ? (zhi) is added to the top of ? as a phonetic marker.

The character ?/? is pronounced chi, and can also mean gears, cogs, or age.

Mandarin Vocabulary With Chi

Traditional Characters	Simplified Characters	Pinyin	English
??	??	yá chi	dental; tooth
??	??	chi lun	(machine) gear
??	??	bào chi	gear-shaping
??	??	bù chi	to despise; to hold in contempt
????	????	lòu chi ér xiào	grin
??	??	shàng chi	upper teeth
??	??	xià chi	lower teeth