A small corner or nook of a room or place; a spot at the edge or corner (colloquial).
猫が部屋の隅っこで丸くなって眠っている。
The cat is curled up and sleeping in the corner of the room.
子どもは家の隅っこでおもちゃを並べて遊んでいた。
The child was playing, lining up toys in a corner of the house.
大勢の前で話すのは嫌なので、いつも隅っこに座る。
I don't like speaking in front of many people, so I always sit in the corner.