If someone gives you a penetrating look, it makes you think that they know what you are thinking. He gazed at me with a sharp, penetrating look that made my heart pound. = piercing
tending to penetrate; having the power of entering or piercing; "a toxic penetrative spray applied to the surface"; "a cold penetrating wind"; "a penetrating odor"
Having the power of entering, piercing, or pervading; sharp; subtile; penetrative; as, a penetrating odor
having or demonstrating ability to recognize or draw fine distinctions; "an acute observer of politics and politicians"; "incisive comments"; "icy knifelike reasoning"; "as sharp and incisive as the stroke of a fang"; "penetrating insight"; "frequent penetrative observations"
A penetrating sound is loud and usually high-pitched. Mary heard the penetrating bell of an ambulance = piercing
Someone who has a penetrating mind understands and recognizes things quickly and thoroughly. a thoughtful, penetrating mind