Beatniks were young people in the late 1950's who rejected traditional ways of living, dressing, and behaving. People sometimes use the word beatnik to refer to anyone who lives in an unconventional way.
...a beatnik art student.
beatnik in British English
(ˈbiːtnɪk)
noun
1.
a member of the Beat Generation (sense 1)
2. informal
any person with long hair and shabby clothes
Word origin
C20: from beat (n) + -nik, by analogy with Sputnik