呒

呒 has two completely different uses. (1) In Wu-family dialects (Shanghainese, Suzhou, Ningbo) it's pronounced m and means 'not have / no,' equivalent to Mandarin 没有 — you'll see it in dialect literature and on Shanghai signage as 呒没 'don't have.' (2) In classical Chinese it's pronounced fǔ and means 'astonished, perplexed,' as in 呒然 'taken aback.' The dialect sense is the one a learner is overwhelmingly more likely to encounter.

The 口 (mouth) radical signals it's a sound-word — exactly the closed-lip 'mm' Wu speakers actually use for negation. Its existence in CC-CEDICT and the Xinhua dictionary tradition is rare among dialect particles, reflecting Shanghai's outsized cultural footprint.