In linguistics, the study of quantity is concerned with the behavior of expressions that refer to amounts in terms of the internal structure of objects and events, their spatial or temporal extension (as duration and boundedness), their qualifying properties, as well as how these aspects interact with each other and other linguistic phenomena. Quantity is primarily manifest in language for the lexical categories of noun, verb, and adjective/ adverb. For instance, the distinction between mass and count nouns is essentially quantitative: it indicates how nominal denotation is quantized—as substance (e.g., water, sand) or as an atomic individual (e.g., book, boy). Similarly, the aspectual classes of verbs, such as states (know), activities (run), accomplishments (drown), achievements (notice), and semelfactives (knock) represent quantitatively different types of events. Adjectives and adverbs may lexically express quantities in relation to individuals, respectively, events (e.g., little, enough, much, often), and one might argue that numerals (two, twenty) are intrinsic quantitative expressions. Quantitative derivation refers to the use of derivational affixes to encode quantity in language. For instance, the English suffix -ful attaches to a noun N1 to derive another noun N2, such that N2 denotes the quantity that fits in the container denoted by N1. N2 also employs a special use in quantitative constructions: see hand—a handful of berries. The challenge for the linguistic description of quantity is that it often combines with other linguistic notions such as evaluation, intensification, quality, and it does not have a specific unitary realization—it is usually auxiliary on other more established notions. Quantitative affixes either have limited productivity or their primary use is for other semantic notions. For instance, the German suffix ‑schaft typically forms abstract nouns as in Vaterschaft ‘fatherhood’, but has a (quantity-related) collective meaning in Lehrerschaft ‘lecturer staff’; compare English -hood in childhood and the collective neighborhood. This diversity makes quantity difficult to capture systematically, in spite of its pervasiveness as a semantic notion.
The category of Personal/Participant/Inhabitant derived nouns comprises a conglomeration of derived nouns that denote among others agents, instruments, patients/themes, inhabitants, and followers of a person. Based on the thematic relations between the derived noun and its base lexeme, Personal/Participant/Inhabitant nouns can be classified into two subclasses. The first subclass comprises derived nouns that are deverbal and carry thematic readings (e.g., driver). The second subclass consists of derived nouns with athematic readings (e.g., Marxist). The examination of the category of Personal/Participant/Inhabitant nouns allows one to delve deeply into the study of multiplicity of meaning in word formation and the factors that bear on the readings of derived words. These factors range from the historical mechanisms that lead to multiplicity of meaning and the lexical-semantic properties of the bases that derived nouns are based on, to the syntactic context into which derived nouns occur, and the pragmatic-encyclopedic facets of both the base and the derived lexeme.
Derivational morphology is a type of word formation that creates new lexemes, either by changing syntactic category or by adding substantial new meaning (or both) to a free or bound base. Derivation may be contrasted with inflection on the one hand or with compounding on the other. The distinctions between derivation and inflection and between derivation and compounding, however, are not always clear-cut. New words may be derived by a variety of formal means including affixation, reduplication, internal modification of various sorts, subtraction, and conversion. Affixation is best attested cross-linguistically, especially prefixation and suffixation. Reduplication is also widely found, with various internal changes like ablaut and root and pattern derivation less common. Derived words may fit into a number of semantic categories. For nouns, event and result, personal and participant, collective and abstract noun are frequent. For verbs, causative and applicative categories are well-attested, as are relational and qualitative derivations for adjectives. Languages frequently also have ways of deriving negatives, relational words, and evaluatives. Most languages have derivation of some sort, although there are languages that rely more heavily on compounding than on derivation to build their lexical stock. A number of topics have dominated the theoretical literature on derivation, including productivity (the extent to which new words can be created with a given affix or morphological process), the principles that determine the ordering of affixes, and the place of derivational morphology with respect to other components of the grammar. The study of derivation has also been important in a number of psycholinguistic debates concerning the perception and production of language.