one 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

to decide that somebody/something belongs to a particular group or type without thinking deeply enough about it and considering what other qualities they might have

to decide to deal with something later or to forget it

<i>She pigeonholed her worry about him.</i>

<i>Plans for a new school have been pigeonholed.</i>

LEARNit Dictionary