IPA: /dɪˈsiːtfəl.nəs/
KK: /dɪˈsitfəl/
The condition of being dishonest or misleading in order to trick someone.
His deceitfulness led to a loss of trust among his friends.
Deceitfulness → It is formed from "deceit" (from Old French *deceite*, meaning deception or trickery) and "-fulness" (meaning the state of being full of). The word "deceitfulness" refers to the state of being full of deceit or trickery.
Think of 'deceit' as trickery and '-fulness' as being full of something — so deceitfulness means being full of trickery.