In linguistics, an object is any of several types of arguments. In subject-prominent, nominative-accusative languages such as English, a transitive verb typically distinguishes between its subject and any of its objects, which can include but are not limited to direct objects, indirect objects, and arguments of adpositions (prepositions or postpositions); the latter are more accurately termed oblique arguments, thus including other arguments not covered by core grammatical roles, such as those governed by case morphology (as in languages such as Latin) or relational nouns (as is typical for members of the Mesoamerican Linguistic Area). In ergative-absolutive languages, for example most Australian Aboriginal languages, the term "subject" is ambiguous, and thus the term "agent" is often used instead to contrast with "object", such that basic word order is described as agent–object–verb (AOV) instead of subject–object–verb (SOV). Topic-prominent languages, such as Mandarin, focus their grammars less on the subject-object or agent-object dichotomies but rather on the pragmatic dichotomy of topic and comment.

In English traditional grammar types, three types of object are acknowledged: direct objects, indirect objects, and objects of prepositions. These object types are illustrated in the following table:

Indirect objects are frequently expressed as objects of prepositions, complicating the traditional typology; e.g. "I gave salt to the man."

Some Chinese verbs can have two direct objects, one being more closely bound to the verb than the other; these may be called "inner" and "outer" objects.

Secundative languages lack a distinction between direct and indirect objects, but rather distinguish primary and secondary objects. Many African languages fall into this typological category.

Several Slavic and agglutinating languages (e.g. Turkish, Hungarian, Finnish) use their case systems to differentiate between direct and indirect objects. The former is usually expressed in the accusative case, while the latter in the dative or allative case. Because of the structure of dative words in Hungarian, indirect objects are rather categorised as adjuncts, not objects.

While the typical object is a pronoun, noun, or noun phrase, objects can also appear as other syntactic categories, as illustrated in the following table for the English language:

A number of criteria can be employed for identifying objects, e.g.: