- 1one of a set of small boxes that are fixed on a wall and open at the front, used for putting letters, messages, etc. in; one of a similar set of boxes that are part of a desk, used for keeping papers, documents, etc. in
- 2(disapproving) a group or type that someone or something is considered or described as belonging to, even when this is not accurate or not fair and does not take account of their individual qualities She doesn't fit into a convenient musical pigeonhole. Those were the ethnic pigeonholes we put people in then.