Just like other semantic subtypes of nouns such as event nouns or agent nouns, collectives may be morphologically opaque lexemes, but they are also regularly derived in many languages. Perhaps not a word-formation category as productive as event nouns or agent nouns, collective nouns still represent a category associated with particular means of word formation, in the case of the Romance languages by means of derivational suffixes. The Romance languages all have suffixes for deriving collectives, but only very few go directly back to Latin. In most cases, they evolve from other derivational suffixes via metonymic changes of individual derived nouns, notably event nouns and quality nouns. Due to the ubiquity of these changes, series of semantically and morphologically equivalent collectives trigger functional changes of the suffixes themselves, which may then acquire collective meaning. Most of these suffixes are pan-Romance, in many cases going back to very early changes, or to inter-Romance loans. The different Romance languages have overlapping inventories of suffixes, with different degrees of productivity and different semantic niches. The ease of transition from event or quality noun to collective also explains why only few suffixes are exclusively used for the derivation of collective nouns.
In morphology, the two labels ‘collective’ and ‘abstract’ have been used to refer to properties and categories relevant at different levels. The term collective is normally used in connection with number and plurality in reference to a plurality presented as a homogeneous group of entities. This can be relevant for inflectional morphology where it can be shown to flank markers for coding number in some languages. Moreover, a plurality intended as a homogeneous group of individuals can also be relevant for word-formation patterns where it usually expresses concrete or abstract sets of objects relating to the derivational base. The term abstract makes general reference to processes of nominalization from different source classes, especially verbs and adjectives. In the passage to the nominal domain, verbal properties like tense and argument structure are partially lost while new nominal properties are acquired. In particular, a number of semantic shifts are observed which turn the abstract noun into a concrete noun referring to the result, the place, etc. relating to the derivational base. Although the morphological processes covered by the two labels apparently depict different conceptual domains, there is in fact an area where they systematically overlap, namely with deverbal nouns denoting an abstract or concrete, iterated or habitual instantiation of the action referred to by the verbal base, which can be conceptualized as a collective noun.