Uninvited means turning up without having been asked. An uninvited guest, arrive uninvited, uninvited advice.
It reaches beyond guests: uninvited advice and uninvited attention are both things nobody asked for, and the word is how English says so politely. The adverb use, walking in uninvited, is as common as the adjective.
1adjectiveuninvitedTurning up without having been asked.
“Two uninvited guests turned up at the wedding and ate half the cake.”
uninvited is a quality.
From un- + invited.
Etymology from Wiktionary, CC BY-SA