IPA: //frɒˈtɜːr//
KK: /fro-tur/
A person who rubs against someone else for sexual pleasure, often in a public place.
The frotteur was caught in the crowded subway, causing discomfort to the passengers.
Frotteur comes from the French word 'frotter' (meaning to rub) combined with the suffix '-eur' (indicating a person who performs an action). The term refers to a person who derives sexual pleasure from rubbing against another person in a crowded place.
Think of someone who 'rubs' ('frotter') against others in a crowd — that's how 'frotteur' describes that person.