feigned ignorance; pretending not to know; ignoring
Describes the act of deliberately ignoring someone or something, often by pretending not to notice. Commonly used in the phrase 知らぬ顔をする.
See also: 知らん顔
He pretended not to know me even though he saw me.
Even when someone is in trouble, many people pass by with feigned ignorance.
unconcerned air; indifference; nonchalance
Refers to an attitude of not caring or being indifferent, often shown by a blank or unconcerned expression. Can overlap with sense 1 but emphasizes the emotional state rather than the act of ignoring.
No matter what happens, she sits there with an unconcerned air.
Compound of 知らぬ (negative form of 知る, 'to know') and 顔 ('face'). The expression literally means 'a face that does not know'.