Accidence: the part of grammar that deals with changes in words to change their meaning, for example, adding endings to verbs or changing their spelling to indicate different tenses (walk/walked, run/ran,go/went), adding letters to nouns or changing their spelling to indicate number (boy/boys, man/men), and spelling pronouns differently to indicate subject or object. “Has went†and “between you and I†are examples of errors of accidence.