A defective verb refers to a verb that is lacking certain tenses or forms that are commonly found in regular verbs. Instead of using the defective verb, one can opt for synonyms such as "irregular verb" or "incomplete verb." These terms describe verbs that don't follow the standard conjugation rules or that are missing certain forms, making them less versatile than regular verbs. Additionally, "weak verb" is another synonym that can be used to describe defective verbs, as these types of verbs tend to have a limited range of inflections and may be considered less powerful than their regular counterparts. Overall, using synonyms for defective verbs can help provide clarity and precision in written and spoken language.