Word-formation encompasses a wide range of processes, among which we find derivation and compounding, two processes yielding productive patterns which enable the speaker to understand and to coin new lexemes. This article draws a distinction between two types of constituents (suffixes, combining forms, splinters, affixoids, etc.) on the one hand and word-formation processes (derivation, compounding, blending, etc.) on the other hand but also shows that a given constituent can appear in different word-formation processes. First, it describes prototypical derivation and compounding in terms of word- formation processes and of their constituents: Prototypical derivation involves a base lexeme, that is, a free lexical element belonging to a major part-of-speech category (noun, verb, or adjective) and, very often, an affix (e.g., Fr. laverV ‘to wash’ > lavableA ‘washable’), while prototypical compounding involves two lexemes (e.g., Eng. rainN + fallV > rainfallN). The description of these prototypical phenomena provides a starting point for the description of other types of constituents and word-formation processes. There are indeed at least two phenomena which do not meet this description, namely, combining forms (henceforth CFs) and affixoids, and which therefore pose an interesting challenge to linguistic description, be it synchronic or diachronic. The distinction between combining forms and affixoids is not easy to establish and the definitions are often confusing, but productivity is a good criterion to distinguish them from each other, even if it does not answer all the questions raised by bound forms. In the literature, the notions of CF and affixoid are not unanimously agreed upon, especially that of affixoid. Yet this article stresses that they enable us to highlight, and even conceptualize, the gradual nature of linguistic phenomena, whether from a synchronic or a diachronic point of view.