céng, zēng
already
Pictograph of a cooking pot. Based on the original meaning "cauldron; cooking pot", now written as 甑. The current meaning is a phonetic loan.
Evolution

Oracle script
(~1250-1000 BC)
Bronze script
Early Western Zhou (~1000 BC)
Seal script
Shuowen (~100 AD)
Clerical script
Western Han dynasty (202 BC-9 AD)Regular script
ModernDefinitions
Sources