Webster's Revised Unabridged Dictionary · 1913

Penetration

Penetration , noun

[Latin penetratio: compare French pénétration.]

1.
The act or process of penetrating, piercing, or entering; also, the act of mentally penetrating into, or comprehending, anything difficult.
And to each in ward part, With gentle penetration, though unseen, Shoots invisible virtue even to the deep. — Milton
A penetration into the difficulties of algebra. — Watts
2.
Acuteness; insight; sharp discoverment; sagacity; as, a person of singular penetration. — Walpole