Hip

Hip is an American slang expression that dates from the late 19th/early 20th century and is a term of approbation that means 'with it' or informed. Its origin is obscure but is thought to derive from the slightly earlier word 'hep' which meant the same thing. 'Hep cat' in the 1930s was an American expression for a fan or admirer of jazz but has now largely died out. 'Hip' seems to have generally replaced 'hep' but no one really knows why.