5 [countable] if you are on someone’s side, you support them in an argument or a fight
on someone’s side:
Don’t get annoyed with me – I’m on your side!
take someone’s side (=to support one person rather than another one):
Mary always takes your side.
take sides (=to show support for one person and not others):
I’m not taking sides in this argument.
Synonyms and related words