''If'' is an English preposition, as seen in ''If it's sunny tomorrow, ''(''then'')'' we'll have a picnic''. As a preposition, ''if'' normally takes a clausal complement (e.g., ''it's sunny tomorrow'' in ''if it's sunny tomorrow''). That clause is, within the conditional construction, the condition (or protasis) on which the main clause (or apodosis) is contingent. In such cases, ''if'' can be paraphrased as "in case" or "contingent on the case that". ''If it's sunny tomorrow'' is a

preposition phrase An adpositional phrase is a syntactic category that includes ''prepositional phrases'', ''postpositional phrases'', and ''circumpositional phrases''. Adpositional phrases contain an adposition (preposition, postposition, or circumposition) as he ...

, and within a conditional construction it functions as an adjunct. Where ''if'' takes a

noun phrase A noun phrase – or NP or nominal (phrase) – is a phrase that usually has a noun or pronoun as its head, and has the same grammatical functions as a noun. Noun phrases are very common cross-linguistically, and they may be the most frequently ...

(NP) or

adjective phrase An adjective phrase (or adjectival phrase) is a phrase whose Head (linguistics), head is an adjective. Almost any grammar or syntax textbook or dictionary of linguistics terminology defines the adjective phrase in a similar way, e.g. Kesner Bland ( ...

(AdjP) complement, the construction is concessive rather than conditional: ''The ascent was exhilarating, if ''_NP 'a challenge''_AdjP 'challenging''. Traditional grammar books commonly treat ''if'', often understood as a single word encompassing both this preposition and the homonymous subordinator, as a "

subordinating conjunction In grammar, a conjunction (abbreviated or ) is a part of speech that connects words, phrases, or clauses'','' which are called its conjuncts. That description is vague enough to overlap with those of other parts of speech because what constitute ...

", a category covering a broad range of clause-connecting words.

References

{{Reflist English words Prepositions

See also

References