Here's the sentence: He's pretending that he didn't know anything. He is _____.
What is the adjective for someone who pretends? Pretender is a noun. Is it pretentious? But the meaning of it is:
1: characterized by pretension: such as
making usually unjustified or excessive claims (as of value or standing)
the pretentious fraud who assumes a love of culture that is alien to him — Richard Watts
expressive of affected, unwarranted, or exaggerated importance, worth, or stature
pretentious language pretentious houses
2 : making demands on one's skill, ability, or means : ambitious
the pretentious daring of the Green Mountain Boys in crossing the lake — Amer. Guide Series: Vt.