feigning ignorance; pretending not to know; playing innocent
Used when someone acts as if they are unaware of something, often to avoid responsibility or confrontation. The phrase is a fixed expression, typically followed by をする or でいる.
He pretended not to know about my question.
She passed by me, pretending not to recognize me.
Standard kanji-kana mixed spelling.
Common variant with ふり in kana.
Variant with そ in kana.
Variant with そ in kana and 振り in kanji.
Variant with そしらぬ in kana and 振り in kanji.
The phrase combines 素 (here meaning 'plain' or 'unadorned') with the negative form of 知る (to know) and 振り (pretense). The exact historical derivation is uncertain, but it is a fixed idiomatic expression.