Webster's Revised Unabridged Dictionary · 1913

Intension

Intension , noun

[Latin intensio: compare French intension. See Intend, and compare Intention.]

1.
A straining, stretching, or bending; the state of being strained; as, the intension of a musical string.
2.
Increase of power or energy of any quality or thing; intenseness; fervency. — Jer. Taylor
Sounds... likewise do rise and fall with the intension or remission of the wind. — Bacon
3.
(Logic & Metaphysics) The collective attributes, qualities, or marks that make up a complex general notion; the comprehension, content, or connotation; -- opposed to extension, extent, or sphere.
This law is, that the intension of our knowledge is in the inverse ratio of its extension. — Sir W. Hamilton