/ ˈsɪnfl; NAmE / adjective
morally wrong or evil
SYN immoral :
sinful thoughts
It is sinful to lie.
( informal )
It's sinful to waste good food!
► sin·ful·ly / -fəli; NAmE / adverb
► sin·ful·ness noun [ U ]
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WORD ORIGIN
Old English synfull (see sin , -ful ).