thumbnail sketch; brief character portrait
A concise, vivid description of a person's character or appearance, often used in literary or journalistic contexts.
His essay contains several thumbnail sketches of his acquaintances.
人物描写 is a broader term for character depiction in general, while 人物寸描 specifically implies a concise, sketch-like portrayal.
Compound of 人物 (person, character) and 寸描 (brief sketch, from 寸 'a little' and 描 'depict').