Deceitful

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Middle English: from Old French, past participle (used as a noun) of deceveir ‘deceive’.

wiktionary

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deceit +‎  -ful

etymonline

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deceitful (adj.)

"full of deceit, tending to mislead," mid-15c., from deceit + -ful. Earlier in the same sense was deceivant (late 14c.). Related: Deceitfully; deceitfulness.