Intension

A straining, stretching, or bending; the state of being strained; as, the intension of a musical string.

Increase of power or energy of any quality or thing; intenseness; fervency.

The collective attributes, qualities, or marks that make up a complex general notion; the comprehension, content, or connotation; -- opposed to extension, extent, or sphere.

what you must know in order to determine the reference of an expression