1. uninhibited, lively, fashionable; esp. in phrs. swinging London, swinging ’60s.
2. a general term of approval.
3. pertaining to drug use and culture.
4. aware, ‘on the ball’.
SE in slang uses
1. a person; usu. in phr. every swinging dick; thus phr. swing a big dick, to be influential.
2. an aggressive person.