The true English adverbs are a closed class or marked with a functional morpheme (usually -ly) - he sidled slowly, crablike, into the room. can even act as verbs (when there is no more obvious and appropriate verb to use - he shouldered him aside and headed the ball into the goal he minuted the discussion).

Nouns, parts of the body, time points or durations, etc. Words don't in general belong to a single part of speech (POS), that is POS is not in general a lexical property of a word, but they are normally associated with a particular dominant role/POS which in this (*day) case is Noun (or NP), although like any (prepositional) noun phrase, particularly one locating in space or time it can act as an adverb. Compare: was great.Īpparently the days of the week can also serve as determiners this way: Sunday afternoon. A singular count noun generally needs a determiner in front of it if it's going to function as, say, the subject of a sentence. This is not something pronouns normally do it's an oddball case.ĭeterminers include the bolded expressions in twelve angry men, my red tennis shoes, a sandwich, your father's truck, three or four billion dollars. Here the pronoun yesterday functions as a determiner. That is, certain noun phrases can be tacked onto a sentence in just the same way as an adverb or a prepositional phrase. Several examples are given of noun phrases that specify time: I have an important meeting.

They are sometimes but not always adverbs. In a case like 'I have an important meeting tomorrow,' it seems as if they're nouns.ĬGEL spends several pages on “temporal location expressions”. I suppose they’d say that’s just Shakespeare playing with words.) (It doesn't mention Shakespeare’s “.And all our yesterdays have lighted fools the way to dusty death.” which shows yesterday acting a lot like a noun.

Unlike adverbs and prepositions, they have a possessive form.

Unlike common nouns, they don’t take determiners.

Which day yesterday is depends on the context of the speech act, i.e. It says that yesterday, today, tonight, and tomorrow are pronouns. The Cambridge Grammar of the English Language (CGEL) gives an analysis that differs dramatically from the other answers here.

What part of speech is the word this