What is the definition of 'intensity'?

Answer 1

Intensity :

1. the quality or condition of being intense. 2. great energy, strength, concentration, vehemence, etc., as of activity, thought, or feeling: He went at the job with great intensity. 3. a high or extreme degree, as of cold or heat. 4. the degree or extent to which something is intense. 5. a high degree of emotional excitement; depth of feeling: The poem lacked intensity and left me unmoved. 6. the strength or sharpness of a color due esp. to its degree of freedom from admixture with its complementary color. 7. Physics. magnitude, as of energy or a force per unit of area, volume, time, etc. 8. Speech. a. the correlate of physical energy and the degree of loudness of a speech sound. b. the relative carrying power of vocal utterance.
The word intensity means a force or level of power.

Answer 2

In physics, intensity is a measure of the time-averaged energy flux. The word "intensity" here is not synonymous with "strength", "amplitude", or "level", as it sometimes is in colloquial speech. For example, "the intensity of pressure" is meaningless, since the parameters of those variables do not match.