In grammar, an intensive word form is one which denotes stronger or more forceful action relative to the root on which the intensive is built. Intensives are usually lexical formations, but there may be a regular process for forming intensives from a root. Intensive formations, for example, existed in Proto-Indo-European, and in many of the Semitic languages.
In Classical Arabic, Form II (faʿʿal-a) can form intensives, in addition to causatives; while form IV (afʿal-a) forms only causatives. Hebrew has a similar distinction between the pi`el (intensive) and hiph`il (causative) binyans.
Latin had verbal prefixes e- and per- that could be more or less freely added onto any verb and variously added such meanings as to put a great deal of effort into doing something: ructa (burp), eructa (belch). When the same prefixes, especially per, were added to adjectives, the resulting meaning was very X or extremely X.