noun
interloper; third wheel; hanger-on
Refers to a person who is unwelcome or out of place in a group, often implying they are a burden or nuisance. The term carries a negative connotation.
彼はいつも私たちのグループに余り者みたいに付いてくる。
He always tags along with our group like a third wheel.
パーティーで余り者扱い
I was treated like an interloper at the party and felt very uncomfortable.
Compound of 余り (amari, 'excess, leftover') and 者 (mono, 'person'). The literal meaning is 'leftover person', which developed into the figurative sense of an unwanted extra person in a group.