• Adjuncts are one of the four types of adverbial; the others are subjuncts, disjuncts, and conjuncts.

• Adjuncts are the only adverbials which function similarly to the sentence elements, Subject, Object, and Complement. (In the two basic clause patterns which contain adverbials — Subject + Verb + Adverbial (SVA) and Subject + Verb + Object + Adverbial (SVOA) — the adverbial will always be an adjunct.) There are two main categories of adverbial: predication adverbials and sentence adverbials. (“Predication” refers to the part of a clause (or sentence) which follows the verb element.) The predication category is further divided into two sub-categories: obligatory predication adjuncts and optional predication adjuncts. The second main category of adjuncts is sentence adjuncts. (Whereas predication adjuncts modify the verb element of a sentence or clause, sentence adjuncts apply to a whole clause or sentence.) Adjuncts can be “realized” by a wide range of grammatical structures: adverbial phrases (including single-word adverbs), noun phrases, by finite and non-finite clauses. They can be categorized semantically as adjuncts of space, time, or process.

The distinction between obligatory and optional adverbials is not so much a distinction between adverbials as a distinction between verbs: some verbs require modification by an adjunct; others do not. For example, the verb “live,” although it is normally intransitive, and so cannot be followed by an object, must be followed by an adjunct. For example, “He lived” is not grammatically acceptable whereas, “He lived in the nineteenth century ” is. Two other common verbs which require an adjunct are “walk” and “put”. (“Put” being a transitive verb requires both an object and an adjunct.)

The great majority of transitive verbs can be used without an adjunct, but intransitive verbs that don’t require one are quite rare. Moreover, even in the case of verbs which can be used in this way, there us a tendency for speakers and listeners to feel the need of an adjunct if none is implicit in the context. “Vanish” and “disappear” are examples of such verbs. These verbs do occur without adverbials in sentences such as “The elephant disappeared,” or “The princess vanished,” but they are much more commonly found with adverbials as in “The elephant disappeared, into the forest” or “The princess suddenly vanished.”

The distinction between the two types of predication adverbials on the one hand and sentence adverbials on the other is not really a distinction between adverbials but rather a distinction between the kinds of meaning they can have and consequent differences in grammatical behavior. The sentence, “Harry saw Jill jumping from the top of the building,” is ambiguous. It can be taken to mean that Harry himself was on the top of the building when he saw Jill jumping or that Harry (who was not on the top of the building but able to see it from somewhere else) saw Jill jumping off the roof. If the sentence is interpreted in the first way, then the adverbial “from the top of the building” is a sentence adjunct because it applies to the whole sentence rather than simply to the verb. Although the sentence is ambiguous as it stands, the ambiguity can easily be resolved by “fronting” the sentence adjunct so the sentence becomes: “From the top of the building, Harry saw Jill jumping.” In other words, from a grammatical point of view, sentence adjuncts are distinguished from predication adjuncts by their relative freedom of movement.