zhǐ, zhī
only
Origin unclear. In simplified Chinese, in addition to the meaning "only", 只 is also used as a measure word. In traditional Chinese this meaning is written as 隻.
Evolution

Seal script
Chu (Warring States: 475-221 BC)
Seal script
Shuowen (~100 AD)Regular script
ModernDefinitions
Sources
季旭昇《說文新證》p.149-150