What is "intension"

Intension \In*ten"sion\, n. [L. intensio: cf. F. intension. See Intend, and cf. 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 & Metaph.) 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.

c.1600, from Latin intensionem (nominative intensio) "a stretching, straining, effort," noun of action from past participle stem of intendere (see intend).

n. 1 intensity or the act of becoming intense . 2 (context logic semantics English) Any property or quality connoted by a word, phrase or other symbol, contrasted to actual instances in the real world to which the term applies. 3 (context dated English) A straining, stretching, or bending; the state of being strained.

n. what you must know in order to determine the reference of an expression [syn: connotation]

In linguistics, logic, philosophy, and other fields, an intension is any property or quality connoted by a word, phrase, or another symbol. In the case of a word, the word's definition often implies an intension. For instance, intension of the word '[plant]' includes properties like "being composed of cellulose" and "alive" and "organism," among others. Comprehension is the collection of all such intensions.

The meaning of a word can be thought of as the bond between the idea the word means and the physical form of the word. Swiss linguist Ferdinand de Saussure (1857–1913) contrasts three concepts:

1. the signifier – the "sound image" or the string of letters on a page that one recognizes as the form of a sign
2. the signified – the meaning, the concept or idea that a sign expresses or evokes
3. the referent – the actual thing or set of things a sign refers to. See Dyadic signs and Reference (semantics).

Without intension of some sort, a word has no meaning. For instance, the terms 'rantans' or ' brillig' have no intension and hence no meaning. Such terms may be suggestive, but a term can be suggestive without being meaningful. For instance, 'ran tan' is an archaic onomatopoeia for chaotic noise or din and may suggest to English speakers a din or meaningless noise; and 'brillig' though made up by Lewis Caroll may be suggestive of 'brilliant' or 'frigid.' Such terms, it may be argued, are always intensional since they connote the property 'meaningless term' but this paradox does not constitute a counterexample to the claim that without intension a word has no meaning.

Intension is analogous to the signified in the Saussurean system, extension to the referent.

In philosophical arguments about dualism versus monism, it is noted that thoughts have intensionality and physical objects do not (S. E. Palmer, 1999), but rather have extension in space and time.

Note: Intension and intensionality (the state of having intension) should not be confused with intention and intentionality, which are pronounced the same and occasionally arise in the same philosophical context. Where this happens, the letter s or t is sometimes italicized to emphasize the distinction.