Conjunction

A function word that links words, phrases, or clauses. Conjunctions express relations such as coordination, subordination, and alternatives.

Coordinating conjunction: A conjunction that links grammatical units of equal status, such as words, phrases, or independent clauses. This subtype joins units without making one grammatically dependent on the other.
Coordination (linguistics): A syntactic relation that joins units of equal grammatical status. Conjunctions such as and and but commonly mark this relation.
Logical conjunction: A truth-functional operation that is true only when both of its inputs are true. The word and can express this logical relation, though grammatical conjunction is broader.
Preposition: A function word that typically relates a noun phrase to another element in a clause. Prepositions can introduce phrases, while subordinating conjunctions introduce clauses.
Grammaticalization: The historical process by which words develop grammatical functions or become more grammatical over time. Conjunctions can arise as lexical expressions become markers of clause relations.
Subordinating conjunction: A conjunction that introduces a dependent clause and connects it to a main clause. This subtype marks a clause as grammatically dependent on another.
Subordination (linguistics): A syntactic relation in which one unit depends on another. Subordinating conjunctions introduce clauses that depend on a main clause.
Disjunction: A logical relation that combines propositions as alternatives, commonly expressed with or. Or links alternatives in language and often corresponds to logical disjunction.
Relative pronoun: A pronoun that introduces a relative clause and has a grammatical role within it. Relative pronouns introduce clauses but also fill a role inside those clauses.
Old English: The earliest recorded stage of the English language, used in England before the Norman Conquest. English conjunctions inherit forms and patterns from earlier stages of the language.

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