English Reference
Noun

complainant

n. countable
C1 Advanced US /kəmˈpɫeɪnənt/ UK /kəmplˈeɪnənt/ com·plainant UK spelling complainants Law

n.a person who makes a formal complaint against someone else, especially in a court of law. This is the person who starts a legal case because they feel they were treated unfairly.

n.the party who brings a formal legal charge or complaint against another in a court of law or administrative hearing.


SIMPLE

The complainant gave her statement to the police yesterday.

CONTEXTUAL

During the hearing, the complainant provided several documents to support his claim of unfair dismissal.

COMPLEX

Legal counsel for the defense argued that the complainant had failed to provide sufficient evidence to establish a prima facie case of negligence against the corporation.

Usage

Commonly used in legal and formal administrative contexts; often contrasted with the 'defendant'.

A dispute over a solar panel plan is resolved, with the complainant now a proponent for the site.

BBC News· 18 Aug 2026

Complainant C, the second alleged victim to give evidence, said he told friends and family about the abuse once he had stopped working for Jones.

The Guardian· 17 Aug 2026

From Old French complaignant, present participle of complaindre.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Old French complaignant
Level C1 · Advanced
Frequency Occasional
Updated