Uninviteds are unwelcome guests who show up without being invited. Some synonyms for uninviteds include intruders, gatecrashers, interlopers, and trespassers. Intruder implies someone who enters a space unlawfully or with harmful intentions. Gatecrasher suggests a person who attends a party without an invitation. Interloper describes someone who interferes in a situation they are not welcome in. Trespasser is often used to describe someone who enters private property without permission. These words can be used interchangeably to describe an unwanted presence, and they all convey a sense of intrusion and disregard for boundaries.