get back (Verb) — Recover something or somebody that appeared to be lost. ex. "We got back the money after we threatened to sue the company" ex. "He got back his son from the kidnappers"
get back (Verb) — Take revenge or even out a score. ex. "I cannot accept the defeat--I want to get back"
get back (Verb) — Get one's revenge for a wrong or an injury. ex. "I finally got back with my old enemy"