noun
BAD : In Japan even the big cities are very safety.
GOOD : In Japan even the big cities are very safe.
BAD : She doesn't feel safety when she is on her own.
GOOD : She doesn't feel safe when she is on her own.
BAD : Promise that you will drive safety.
GOOD : Promise that you will drive safely.
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Safety is a noun (NOT an adjective/adverb): 'The boy has been missing for six days, and there are fears for his safety.' 'The firefighters rescued the children and carried them to safety.'