A familiar phenomenon in derivational morphology is potentiation – the creation of new contexts for some affix by the prior addition of some other affix; thus, ‑able potentiates ‑ity in English. Less familiar is the reverse phenomenon of counterpotentiation – the licensing of an affix by the subsequent addition of some other affix. In English, -al counterpotentiates -ic in forms such as whimsical, which has no counterpart in -ic without -al (*whimsic). Facilitatory relations of these two sorts reflect distinct modes of rule combination. The potentiation of an outer rule by an inner rule is a kind of rule composition in which the domain-of-definition of the composite is that of the inner rule; the counterpotentiation of an inner rule by an outer rule is a mode of rule combination in which the domain-of-definition of the combination is disjoint from that of the inner rule. Potentiation enhances conformity to the intermediate well‑formedness criterion; counterpotentiation is a deviation from this criterion.

This chapter considers types of word formation that are not found in English and languages that might be more familiar to students. We look at infixation, circumfixation and parasynthesis, internal stem change (ablaut and consonant mutation), reduplication (full and partial), templatic (root and pattern) morphology, and subtractive processes. Students are introduced to techniques for analyzing morphological data in languages that may be unfamiliar to them.