矮(ǎi) - short (height), low in Mandarin

矮 (ǎi) means "short", used both for a person's height and for how low an object stands: 他很矮 (tā hěn ǎi), "he's short", or 桌子很矮 (zhuōzi hěn ǎi), "the table is low". Its opposite is 高 (gāo, "tall, high"), and the pair 高矮 (gāo ǎi) together can mean "height" as an abstract noun, mirroring how 胖瘦 (pàng shòu, "build") and 宽窄 (kuān zhǎi, "width") are built from opposite pairs.

Applied to people, 矮 (ǎi) is a plain physical description rather than an insult in itself, though as with any physical-description word in any language, tone and context decide whether it lands as neutral or rude - safer to let someone describe their own height first if you are unsure.

Do not confuse 矮 (ǎi) with 低 (dī, "low"): 矮 (ǎi) describes something's own height (a short person, a low table), while 低 (dī) more often describes a position or level relative to something else (a low shelf, a low voice, a low score).