Stress shifting affix

Stress shifting affixes is a term which refers to one of the most characteristic properties of Class I affixes: the property of having effect on the stress pattern of the base.

Example
if we add the affix -ity to the word prodúctive, the suffix attracts stress to the syllable immediately preceding it (productívity). Stress shift to the last syllable of the base is a prone characteristic of this type of affixes. Stress shifting affixes are distinguished from stress neutral affixes.

Links
Utrecht Lexicon of Linguistics