• 無理むり — unreasonable; impossible
• 無事ぶじ — safe; without incident
• 無料むりょう — free of charge
• 無口むくち — reticent; quiet
• 無視むし — to ignore
• 有無うむ — existence or non-existence; yes or no
• 皆無かいむ — nonexistent; absolutely none

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無 expresses negation or absence. The lower dots are the fire component 灬（れっか）. Historically the form shifted and came to represent the abstract idea of “not / none.”