1. [20C+] sophisticated, aware, in tune with events, ideas and situations; often as hip to.
2. [1940s–50s] (US) insolent, cheeky.
3. [1940s+] (US black) splendid, enjoyable.
4. [1960s+] (US black) in possession of or able to supply drugs.
a slang term used by those who are hip.
see hep-cat n.
[20C+] to understand, to recognize, to work out.
[1930s–60s] to be sophisticated, aware.
[1930s] (US black) to be relaxed.
[1950s] (US black) to the greatest extent, e.g. dressed up in one’s best clothes.
[1970s] (US) to understand, to appreciate.
[1990s+] very fashionable, well-dressed.