IPA: /ˈkwɔːr.əl.ər/
KK: /ˈkwɔrələr/
A person who frequently argues or fights with others.
The quarreller always seemed to find a reason to disagree with everyone.
Quarreller → It is formed from "quarrel" (from Old French *quarrel*, meaning a dispute or argument) and "-er" (meaning a person who). A quarreller is a person who engages in disputes or arguments.
Think of someone who is involved in a 'dispute' ('quarrel') — the '-er' indicates that this person is actively participating in the argument.