adverb
without noticing; before one realizes; unconsciously
Describes an action or state that occurs naturally, without deliberate thought or awareness. Often used when something happens spontaneously or when one is caught up in a situation.
思わず知らず涙が出た。
Tears came to my eyes before I knew it.
彼の話に思わず知らず引き込まれた。
I was drawn into his story without realizing it.
思わず is more common and means 'involuntarily' or 'without thinking', often for a momentary reaction. 思わず知らず emphasizes a gradual, unconscious process over time.
知らず知らず has a similar meaning of 'unconsciously' or 'without noticing', but 思わず知らず adds the nuance of 'without thinking' as well.
Compound of 思わず (without thinking) and 知らず (without knowing), reinforcing the idea of an unconscious or unnoticed action.