Defective paradigm

Defective paradigm is the situation where some (regular) inflectional forms of a lexical category are missing in a number of words.

Example
Dutch has a class of compound verbs (such as wielrennen (lit. wheelrun) 'bicycling') of which only the infinitive (wielrennen) and the past participle (gewielrend) are used, while other inflected forms are hardly used (*hij wielrent or *hij rent wiel 'he is bicycling'). These compound verbs have a defective paradigm.

Link
Utrecht Lexicon of Linguistics