What is the process of forming new words by combining two or more free morphemes called?

The process of forming new words by combining two or more free morphemes is known as compounding. In linguistics, free morphemes are words that can stand alone with meaning, such as 'book' or 'shelf.' When these morphemes are combined, they create a new word, such as 'bookshelf.' This highlights the productive nature of language, where two existing concepts merge to form a new lexical item with a distinct meaning.

Compounding is a common method in English for creating new terms, particularly in a language that frequently develops new vocabulary through the combination of existing elements. In contrast, other processes like conversion involve altering a word's grammatical category without changing its form, borrowing entails taking words from other languages, and derivation involves adding affixes to base morphemes to create new words. These different processes serve unique roles in the evolution and expansion of a language's vocabulary, but the specific act of joining free morphemes characterizes compounding.