Substituting

/ˈsʌb.stɪ.tjuː.tɪŋ/

Synonyms

  • alternating
  • exchanging
  • replacing
  • superseding
  • swapping

Slang Meanings

Subbing for someone
I'm just subbing for the regular guy while he's on vacation.
Pulling a switch
I ended up pulling a switch and using my old laptop instead.