pre-noun adjectival
feigned; pretending not to know
Used almost exclusively in fixed expressions like 素知らぬ顔 (feigned ignorance face) or 素知らぬ振り (pretending not to know). Describes acting as if one is unaware of something.
He knows about my mistake, but he's putting on a face of feigned ignorance.
She avoided the topic by pretending not to know.
Standard kanji spelling for this pre-noun adjectival.
Variant spelling with the first character in kana; less common but still encountered.
The derivation is uncertain. The first element 素 (そ) may be related to the prefix meaning 'plain' or 'mere', and 知らぬ is the classical negative form of 知る (to know), giving a literal sense of 'not knowing plainly'.