Can "Wow!" be a sentence?

Question

The question is clear. Can "Wow!" be a sentence?

Imagine a hypothetical context where I'd utter something like this:

Wow! What an amazing idea! I should think about a way to push this fix.

We see "wow" in casual speech often. It bears punctuation marks (typically an exclamation mark, denoting the rising intonation) and a capital letter — just like all "regular" sentences.

On the other hand, neither Wow! nor What an amazing idea! contain any verbs. These certainly don't have any parts of speech in the other sentence, so what are they? Are they sentences or clauses? In other words, can "Wow!" be a sentence despite its lack of [any implied] verbs, and subsequently lack of any distinguishable predicates?

Please back up your answers with references.

Answer 1

This question is anything but clear. It's muddled by design. :^) But I'll take a shot at it.

NOAD defines sentence like this:

sentence (n.) a set of words that is complete in itself, typically containing a subject and predicate, conveying a statement, question, exclamation, or command, and consisting of a main clause and sometimes one or more subordinate clauses. (emphasis added)

The word "typically" is crucial; it suggests that the subject and predicate are not "required." Therefore:

Wow!

is a grammatical, legal, legitmate one-word exclamation sentence, consisting of a lone interjection.

For further reading, I recommend taking a look at this answer to a similar question on ELU.

Answer 2

Short answer:

Yes, these are minor sentences. They consist of a single clause that's usually categorized under "minor clauses".

Examples of minor clauses are optatives, conditional fragments, verbless directives, parallel structures, elliptical constructions, vocatives, exclamatives, interjections and other stereotyped expressions and headlines. ^{[1], [2], [3]}

Long answer:

A normal sentence usually consists of a subject and predicate:

{I} {go to school everyday}.
↑              ↑
_{subject      predicate}

However, unlike the popular (?) belief, a sentence does not need a subject and a predicate in order to be a real one. There are a set of irregular forms of sentences referred to as "minor clauses/sentences". The choice between the use of "sentence" versus clause doesn't matter, since these sentences consist of a single clause. Let's look at some definitions:

Minor sentence

A fragmented, elliptical, or incomplete sentence or clause that still conveys meaning. Also called a minor clause, an abbreviated clause, or a sentence fragment. ^[2]

[1] defines "minor clause" in the beginning of Chapter 10: Clause type and illocutionary force under § 10: Minor clause types in page 944 as any form of clauses that don't belong to the major clause types. These would be (with some further assistance from other sources such as the mentioned page in Grammar.About)

1. Optatives

"Optative" is a grammatical mood that tends to overlap with the "subjunctive".

The Optative mood (abbreviated opt) is a grammatical mood that indicates a wish or hope. It is similar to the cohortative mood, and is closely related to the subjunctive mood.
English has no morphological optative, but there are various constructions with optative meaning. ^[4]

Examples:

1. Long live my king!
2. May God be with ye.
3. So be it.

Example one is a subjunctive.

2. Conditional fragments

3. Verbless directives

4. Parallel structures

5. Elliptical constructions

6. Vocatives

7. Exclamatives

8. Stereotyped expressions

9. Interjections

10. Other

<Under construction>

References:

[1] The Cambridge Grammar of English language (CGEL);

[2] Minor sentence – Grammar.About

[3] Major and minor sentences – Wikipedia

[4] Optative mood – Wikipedia

Answer 3

"Wow!" is an interjection offset by an exclamation mark, not necessarily a sentence.

"Wow! Robert just won the Lotto!" Is an emphatic interjection followed by an exclamatory sentence.

"Wow, Ann was 15 minutes late!" Is an exclamatory sentence containing a mild interjection.

See Schoolhouse Rock "Interjections". "...or by a comma when the feeling's not as strong."

Answer 4

As said above, the question is imprecise and depends on context. Others have agreed that it is a sentence, so I will try to assume the opposite opinion.

It is not a sentence, it's an exclamation. In school I was taught to answer in full sentences. Saying "Five!" was not acceptable. "Yes." is in a different category than "Yes!" as in "Yes! I did it." As was pointed out above, it might be a minor sentence, but I'd say it's still not a fully qualified sentence. If it is not ambiguous and you don't have to shout(!) to get the point across, just use a full stop instead.

In mathematical predicate logic, false and true are predicates on their own. Now I could go on about zeroth-order logic [1], but I don't want to make too many mistakes. The point is, could you write a complete text only of exclamations? Doubt it! I mean, I doubt it, not that you should, but the interpretation as imperative would actually be the most common use of the exclamation mark. Otherwise it's more like "wow ... did you see that?" (not fully quallified on it's own). So it depends on context.

[1] https://en.wikipedia.org/wiki/Zeroth-order_logic

Edit: Of course, "Wow!" can also be understood imperative.

Anyhow, a minor sentence seems rather colloquial. In any formal setting where the distinction between a sentence or something else would matter, colloquial styles would be mistaken.

Edit to address @J.R.'s comment: In mathematical predicate logic, "true" as well as "true -> true" (implication) are predicates, but "true ->" is syntactically incorrect. I allude that the exclamation mark likewise expresses semantic meaning that requires some consequence. The meaning is implicit and hence not an explicit sentence i.e. formally incomplete. The exclamation mark distinctly symbolises the difference to a sentence. Otherwise, I don't see a difference between "Yes." and "Yes!". The distinction is indicative vs imperative.

Of course, this is an argument by analogy and therefore debatable. Also, that's highly formal, therefore use of a single word exclamation could be precluded for style reasons alone.