(1):
(n.) The collective attributes, qualities, or marks that make up a complex general notion; the comprehension, content, or connotation; - opposed to extension, extent, or sphere.
(2):
(n.) A straining, stretching, or bending; the state of being strained; as, the intension of a musical string.
(3):
(n.) Increase of power or energy of any quality or thing; intenseness; fervency.