Intension of a term are the meanings associated with a it by the way and manner it is referred to, as opposed to the meaning resulting from the extension of the term in the respective context.
For example, the terms “morning star” and “evening star” both have the same extension (namely the planet Venus), but different intensions, namely that they describe the appearance of Venus in the morning and evening skies respectively.
- Opaque context
In the broadest sense are intensions of a term those associated meanings that are added by the way and manner in which the term refers to it’s extension.
This includes, as in the example above, the connotations that are associated with the term (e.g “evening” with “evening star”), but also contextual information (as in “masked man” versus “your own father”).
Disregarding this the intensional level of meanings of a term can result in logical errors (intensional fallacy).
- Extensional and intensional definitions on Wikipedia