Literally, “at [the] thought [of]”.
na myśl (not comparable)
- Used other than figuratively or idiomatically: see na, myśl.
- (idiomatic) at the thought [+ o (instrumental) = of something]
- na myśl in Wielki słownik języka polskiego, Instytut Języka Polskiego PAN
- na myśl in Polish dictionaries at PWN