"semi-solid substance," 1899, as a chemical term, short for gelatin and perhaps influenced by jell. The invention of this word is credited to Scottish chemist Thomas Graham (1805-1869). Hair-styling sense is from 1958.
c. 1500, "address with a title;" 1560s, "to give a name to," from style (n.). Meaning "to arrange in (fashionable) style" (especially of hair) is attested from 1934. Slang sense of "act or play in a showy way" is by 1974, U.S. Black slang. Related: Styled; styling.
