1. [late 19C+] (orig. US, also dudelet) a man, a fellow; post 1980s, a person, irrespective of gender.
2. [late 19C+] (orig. US) an overdressed, showy person, a fop or dandy.
3. [late 19C] (Aus.) a womanizer.
4. [1900s] (US campus) a fool.
5. [1910s] (US) an expert.
6. [1920s] an excellent example.
7. [1950s+] (US) a thing.
8. [1960s+] a form of address.
see sense 1 above.
[1980s] (US) a person, irrespective of gender.
[late 19C+] (US) a girl, a woman; often with a suggestion of stylishness or ostentation.
[late 19C+] smart, dandyish.
[1960s] (US) an important person.
[20C+] (US) to dress (oneself) up.