As children learn more words, storing them in memory and producing them as needed, they begin to identify and analyze the meanings of parts of complex words – affixes (prefixes, suffixes, infixes) and roots or stems. Once children can analyze the internal structure of words, they can make use of stems and affixes as building blocks for new words to convey new meanings. To exploit this resource, though, children must be able to analyze words into their constituent parts, assign meanings to those parts, and learn which combinations of parts are allowed in the language they are acquiring.
Languages differ in which types of stem and affix combinations they license and in the meanings conveyed by different patterns in word formation. Languages may rely extensively on compounding or the combination of word roots, as in sun-dial or rabbit-hole; on derivation or the combination of word roots with affixes, as in green-ish or re-read; or both, as in shoe-maker or watering-can. If some options are easier to acquire than others, this should show up in how children acquire different patterns of word formation.
The focus in this chapter is on children's acquisition of compounding and derivation in word formation, as displayed in their coinages to fill gaps in their current vocabulary. After a brief review of the options for compounding and derivation, I look at a variety of languages for when children analyze and understand specific word-formation options and when they begin to use them to coin new words.
Compounding and derivation
Within a language, compound forms are usually divided into types according to their syntactic class. In English, one finds compound nouns formed from roots only (often called root compounds), as in the established forms sun-rise, push-chair, and dog-sled. One also finds some compound adjectives (e.g., grey-eyed, wine-dark) and compound verbs (e.g., to side-step, to dry-clean). Compounding in new adjective and verb formation is rare compared to new noun formation. Compounds in English may also combine affixes and roots, as in the established terms clock-mender or washing-machine. (These are called synthetic compounds.) Compound nouns like snow-flake contain a head (here, flake) and a modifier of that head (namely, snow-); the head element carries number marking, and, in many languages, case and gender marking too.