A person who habitually finds fault and criticizes others or things, often unfairly or excessively.
Compound noun from 'fault' and 'finder' (one who finds), creating a term for a chronic complainer. The word became more common in the 19th-20th centuries.
A 'faultfinder' is basically a professional complainer—they could walk into a perfect situation and still spot something wrong, which is why it's become a bit of a dated but very useful word for describing that one person in every group.
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