In linguistics, a suprafix is a type of affix that adds a suprasegmental pattern (such as tone or stress) to a neutral base in order to convey a derivational or inflectional meaning. For example, a number of African languages express tense / aspect distinctions by tone. The term was suggested by Eugene Nida and taken up in Peter Matthews' influential morphology textbook but is not very widely used. Some linguists prefer superfix, which was introduced by George L. Trager for the stress pattern of a word, which he regarded as a special morpheme that combines and unifies the parts of a word.
In many cases, it is more appropriate to assume that the base has a tone or stress pattern which is replaced by another in inflection or derivation. An example in English is initial-stressed nouns that are derived from verbs with final stress (e.g. prodúce /prəˈdjuːs/ > próduce /ˈprɒdjuːs/). Another is the Mandarin 好 hǎo ("to be good") and 好 hào ("to find good"), where the tone changes from low to falling. Some linguists use suprafix for such a suprasegmental change (in fact, Nida himself considered a distinction between additive suprafixes and replacive suprafixes).