Definition of Big Mac in US English:

Big Mac

noun

US
  • 1A trademark for: the largest in a range of hamburgers sold by McDonald's fast-food outlets; (hence allusively) the biggest or best of a number of related things.

  • 2A nickname for: the Municipal Assistance Corporation of New York City (now disused).

Origin

1960s; earliest use found in Life. From big + mac-.

Pronunciation

Big Mac

/ˈbɪɡ mak/