Auxiliary verbAn auxiliary verb (abbreviated ) is a verb that adds functional or grammatical meaning to the clause in which it occurs, so as to express tense, aspect, modality, voice, emphasis, etc. Auxiliary verbs usually accompany an infinitive verb or a participle, which respectively provide the main semantic content of the clause. An example is the verb have in the sentence I have finished my lunch. Here, the auxiliary have helps to express the perfect aspect along with the participle, finished.
Defective verbIn linguistics, a defective verb is a verb that either lacks a conjugated form or entails incomplete conjugation, and thus cannot be conjugated for certain grammatical tenses, aspects, persons, genders, or moods that the majority of verbs or a "normal" or regular verb in a particular language can be conjugated for. That is to say, a defective verb lacks forms that most verbs in a particular language have.
Regular and irregular verbsA regular verb is any verb whose conjugation follows the typical pattern, or one of the typical patterns, of the language to which it belongs. A verb whose conjugation follows a different pattern is called an irregular verb. This is one instance of the distinction between regular and irregular inflection, which can also apply to other word classes, such as nouns and adjectives. In English, for example, verbs such as play, enter, and like are regular since they form their inflected parts by adding the typical endings -s, -ing and -ed to give forms such as plays, entering, and liked.
NominalizationIn linguistics, nominalization or nominalisation is the use of a word that is not a noun (e.g., a verb, an adjective or an adverb) as a noun, or as the head of a noun phrase. This change in functional category can occur through morphological transformation, but it does not always. Nominalization can refer, for instance, to the process of producing a noun from another part of speech by adding a derivational affix (e.g., the noun legalization from the verb legalize), but it can also refer to the complex noun that is formed as a result.
