backup man is a noun meaning "someone who takes the place of another (as when things get dangerous or difficult)". It carries one recorded sense.
someone who takes the place of another (as when things get dangerous or difficult)
“the star had a stand-in for dangerous scenes”
“we need extra employees for summer fill-ins”
Definitions, synonyms and semantic relations for backup man come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.