An exponent is a phonological manifestation of a morphosyntactic property. In non-technical language, it is the expression of one or more grammatical properties by sound. There are several kinds of exponents:
Identity Affixation Reduplication Internal modification Subtraction
Identity The identity exponent is both simple and common: it has no phonological manifestation at all.
An example in English: DEER + PLURAL → deer
Affixation Affixation is the addition of an affix (such as a prefix, suffix or infix) to a word.
Example in English: want + PAST → wanted
Reduplication Reduplication is the repetition of part of a word.
An example in Sanskrit: दा dā ("give") + PRESENT + ACTIVE + INDICATIVE + FIRST PERSON + SINGULAR → ददामि dadāmi (the da at the beginning is from reduplication of dā that involves a vowel change, a characteristic of class 3 verbs in Sanskrit)
Internal modification There are several types of internal modification. An internal modification may be segmental, meaning it changes a sound in the root.
An example in English: STINK + PAST = stank (i becomes a)
An internal modification might be a suprasegmental modification. An example would be a change in pitch or stress.
An example of the latter in English (acute accent indicates stress): RECÓRD + NOUN = récord
Subtraction Subtraction is the removal of a sound or a group of sounds.
An example in French: OEUF /œf/ ("egg") + PLURAL = œufs /ø/ (final f is lost)
References