In grammar, an intensive form of a word is one which denotes stronger or more forceful action as compared with 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 base 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 causitives. Hebrew has a similar distinction between the "pi`el" (intensive) and "hiph`il" (causative) binyans. Some Germanic languages have intensive prefixes or particles that can be attached to verbs; consider German zer-, which adds the meaning of "... into pieces", e.g. reißen "to rip" zerreißen "to rip to pieces".
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". When the same prefixes (per especially) were added onto adjectives, the resulting meaning was "very X" or "extremely X".