不満
ふまん · fuman · JLPT N3 · noun
dissatisfaction
不満 = not + full: never satisfied; fuman sounds like fumin'
満 means full or satisfied, as in 満足 (satisfaction). Put 不 (not) in front and you get not satisfied, so discontent or complaints. Fuman sounds a lot like English fumin', which is what a dissatisfied person is.
不 — single pictograph; bird flying upward
Originally a pictograph in oracle bone script, traditionally interpreted as a bird flying up toward the sky and unable to come down, suggesting negation or refusal. Over time it became the standard negation word in Chinese, used before verbs and adjectives to mean 'not'.