In grammar, an intensifier is a word such as 'very' or 'extremely' which you can put in front of an adjective or adverb in order to make its meaning stronger.
[technical]
intensifier in British English
(ɪnˈtɛnsɪˌfaɪə)
noun
1.
a person or thing that intensifies
2.
a word, esp an adjective or adverb, that has little semantic content of its own but that serves to intensify the meaning of the word or phrase that it modifies: awfully and up are intensifiers in the phrases awfully sorry and cluttered up
3.
a substance, esp one containing silver or uranium, used to increase the density of a photographic film or plate
Compare reducer (sense 1)
intensifier in American English
(ɪnˈtɛnsəˌfaɪər)
noun
1.
something that intensifies
2. Grammar
an intensive word, prefix, etc.
3. Photography
any of several solutions used to increase the printing density of a negative
Examples of 'intensifier' in a sentence
intensifier
The glow of the image intensifier night sights carried by the marksmen.
Seymour, Gerald FIELD OF BLOOD
It flared dully in the image intensifier, the equipment's electronics dampening down the effect.