preposition

preposition, a word that indicates the relationship of a noun, pronoun, or noun phrase (a group of words that function collectively as a noun) to another word or phrase in a sentence. It is one of eight parts of speech in English grammar.

Types of prepositions

Prepositions have a variety of functions and meanings, which can be categorized in a number of ways. Among the simplest schemes is the categorization of prepositions into those of movement, place, and time.

Prepositions of movement indicate motion, direction, or change of location:

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• The ball is rolling into the box.
• The woman will climb onto her motorcycle.
• The fox jumps over the lazy dog.

They differ from prepositions of place, which indicate a location that is static and unchanging:

• The ball is inside the box.
• Cathy will arrive on her motorcycle.
• The fox stands behind the lazy dog.

Prepositions of time add a time reference to a sentence:

• The ball is rolling at this very moment.
• Cathy will arrive in a few minutes.
• The fox jumps over the lazy dog during its nighttime slumber.

Prepositions may also indicate the syntactic function of a noun phrase. For example, the preposition to or for is sometimes used to identify who or what receives the direct object of the action:

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• The boy handed the toy to his baby brother.
• My friend brought a bone for my dog.

Prepositional phrases and the placement of prepositions

By definition, prepositions must govern a noun, pronoun, or noun phrase. The combination of a preposition with such a word or phrase is called a prepositional phrase. The following are examples of prepositional phrases:

• into the box
• at this very moment
• in the classroom
• with his students

A prepositional phrase functions as a syntactic unit that modifies a verb, a noun, or an adjective, depending on its placement in a sentence:

• Prepositional phrase modifying a verb (was): The teacher was in the classroom.
• Prepositional phrase modifying a noun (teacher): The teacher in the classroom was happy.
• Prepositional phrase modifying an adjective (happy): The teacher was happy with his students.

In some cases, words that are usually prepositions are used instead as adverbs:

• A plane is taking off.
• Cathy came over.

The use of off and over in the sentences above is not prepositional, because neither of those words governs a noun, pronoun, or noun phrase. Rather, they modify the meaning of the verb (as part of a construction known as a phrasal verb). In these cases, an additional preposition must be supplied in order to modify the action with a noun other than the subject:

• A plane is taking off from La Guardia Airport.
• Cathy came over on her motorcycle.

Can you end a sentence with a preposition?

Yes.

Even though a preposition is commonly followed by a noun phrase, there are cases where the noun phrase is placed earlier in a sentence to preserve flow or produce a pragmatic effect:

• Aryabhata understood celestial movements but not what stars are made of.
• This is the book that I was looking for.

The idea that sentences cannot end with a preposition originated in the 17th century, when grammarians tried to restrict English expression to the logic of Latin grammar. However, the application of this rule in English often produces awkward or stilted constructions:

• Aryabhata understood celestial movements but not of what stars are made.
• This is the book for which I was looking.

Nonetheless, ending a sentence with a preposition is discouraged in some circumstances, such as when it would make the sentence’s meaning less clear. Moreover, a sentence cannot end with a preposition if the noun, pronoun, or noun phrase that it governs is not present in the sentence at all (a circumstance known as a dangling preposition).