ACCIDENCE. The part of traditional GRAMMAR dealing with INFLECTION (changes in the forms of words to express such grammatical meanings as case, number, and tense). In English, the differences between work, works, worked, working, and between worker, workers, worker's, workers' would be described and explained under accidence. Nowadays, these differences are usually handled in inflectional morphology, a division of MORPHOLOGY (the study of word form) that deals with the formation and uses of inflections.

accidence part of grammar dealing with inflexions. XIV. — L. accidentia (tr. Gr. parepómena ‘accompanying things’), n. pl. of accidēns ACCIDENT, taken as fem. sing.; see -ENCE.