morphology
Morphology is the study of the different forms of a word. In English, the verb ‘fall’ can have the following forms: ‘fall’, ‘falls’, ‘fell’, ‘falling’, ‘fallen’. Both first- and second-language learners may use ‘*falled’ instead of ‘fell’, or ‘she *jealoused me’ instead of ‘she was jealous of me’. (In linguistics, an asterisk* marks an incorrect form.)
