zhù
candle wick
Phonosemantic compound. 火 represents the meaning and 主 represents the sound. Originally written as 主, a pictograph of a torch.
Evolution

Clerical script
Eastern Han dynasty (25-220 AD)Regular script
ModernDefinitions
zhù
candle wick, lamp wick; stick of incense; wick of an oil lamp; to burn (incense etc); classifier for lit incense sticks
Sources