A grammatical modifier is a part of speech that can be removed from a sentence without changing the grammatical correctness of the phrase. Modifiers can be used to change the emphasis or meaning of a phrase, or to add detail or additional information. Adjectives and adverbs are generally present as modifiers in English phrases. The misuse of modifiers can interfere with the correct interpretation of a phrase if it appears to be connected to the wrong word, or to no word at all.
A word, clause, or phrase is defined as a grammatical modifier if it can be removed from a sentence without making the sentence grammatically incorrect. For example, in the sentence "He walked quickly into the room," both the word 'quickly' and the phrase 'into the room' are modifiers. Removing either element, or both, results in a grammatically correct sentence, while removing 'he walked' creates a sentence fragment. In this example, 'he walked' forms the grammatical core of the clause, which the modifiers act upon.
Modifiers are commonly used to provide more detail in a description. They can describe additional actions, intensify subjects and actions, or provide details of settings or objects. The element of a phrase that is modified is known as the head. A modifier may appear before the head as a pre-modifier or after the head as a post-modifier. The head may be the core element of a sentence, or it may be a modifier itself.
The placement of a grammatical modifier in a phrase can affect the meaning communicated by the sentence. For example, the sentences "I just don't know that song" and "I don't just know that song" are both grammatically correct constructions, but they convey quite different meanings. Other modifiers may retain their meanings regardless of their placement within the sentence. For example, there is no real difference in meaning between "She spoke in a low voice" and "In a low voice, she spoke."
A grammatical modifier may lead to confusion if it is improperly placed, resulting in constructions that are grammatically sound but communicate unintended or nonsensical meanings. For example, "Breath coming quickly, the finish line was in sight," is an example of a dangling modifier. The entity whose breath is coming quickly is not described within the sentence, making the meaning of the sentence unclear. The sentence "The jars were filled with honey in the pantry" appears to describe a set of jars which are filled with honey only when kept inside the pantry. This kind of misplaced modifier can often be remedied by placing the modifier closer to the head, as in "The jars in the pantry were filled with honey."