Longman Dictionary of Contemporary English
Wiktionary
n. A tack for attaching paper to a drawing board etc
WordNet
Wikipedia
A thumb tack (North American English) or push pin is a short nail or pin used to fasten items to a wall or board for display and intended to be inserted by hand, generally without the assistance of tools. A variety of names are used to refer to different designs intended for various purpose. Thumb tack and push pin are both sometimes compounded (thumbtack or pushpin) or hyphenated (thumb-tack or push-pin). Thumb tacks made of brass, tin or iron may be referred to as brass tacks, brass pins, tin tacks or iron tacks, respectively. These terms are particularly used in the idiomatic expression to come (or get) down to brass (or otherwise) tacks, meaning to consider basic facts of a situation. Drawing pin or drawing-pin refers to thumb tacks used to hold drawings on drawing boards. Map pin or map tack refers to thumb tacks used to mark locations on a map and to hold the map in place.
Usage examples of "drawing pin".
Arrietty went into the sitting room to put away her diary, and took some time fixing her candle on the up turned drawing pin which served as a holder.
The note to the charwoman was still pinned to the door with a blue-headed drawing pin: research in progress.