Compounding is a highly productive word formation process in TÄ°D. In compounding, two signs are combined as a new unit that is realized as a single lexical item. The signs that make up a compound can appear in an utterance on their own. When inside a compound, these can be reduced or they can be expressed in full form. The various categories of compounding in TÄ°D are further explained below in terms of the phonological, syntactic, and semantic relations of the parts.