I Propose It Is An Expletive
In a strictly technical sense of the word, unnecessary words and syllables are called expletives if they have no apparent purpose other than to serve as filer. The Century Dictionary and Cyclopedia (C.D.C.) gives the fullest definition of the word:
- In rhetoric and grammar, a word or syllable which is not necessary to the sense or construction, or to an adequate description of a thing, but which is added for rhetorical, rhythmical, or metrical reasons, or which, being once necessary or significant, has lost notional force. Expletives of the former kind are usually trite adjectives, added, as in feeble prose or verse, for the mere sound or to fill out a line, or else irrelevant words or terms used for factitious emphasis, as in profane swearing. Expletives of the latter kind are usually particles like the introductory there, used without local reference, and the auxiliary do, used as in the first line of the quotation from Pope. …
u8Expletives their feeble aid do join
And Ten low words oft creep in one dull line. Pope, Essay on Criticism, 1. 346
However some caution needs to be advised when using the word because for this reason, obscene words and profanities are called expletives because they have lost their most literal signification in common use, which is to say that you do not always mean to refer to fecal matter when exclaiming a censurable word such as:
shit, fuck, damn, or bitch
Hence you have editorial notes like "[expletive deleted]" and this definition of the word from The Cambridge Encyclopedia of the English Language by David Crystal (© 1995):
An exclamatory word or phrase, usually obscene or profane.
The reason I mention all of this, and advise caution is because you may confuse many people who only understand expletives as being obscenities.
However, usually implies an expletive does not necessarily need to be obscene, and on page 395 Mr. Crystal refers to the nonsensical utterance "shlumfnoooeeah" as an expletive in the Deviantly Normal sidebar.
In the technical sense the word, Expletive might not not necessarily need to be exclamatory. The Century Dictionary and Cyclopedia makes reference to the auxiliary verb do, and introductory there. The Columbian Guide to Standard American English by Kenneth Wilson (© 2005) specifically uses the sentence "There is another sailboat." as an example of a sentence which uses the introductory there, which it categorized as a dummy subject and an adverb, as an example of an expletive, in its secondary entry for the word. The O.E.D. Online notes an obsolete subsense of the word referring to a conjunction that supplies or completes the meaning of the foregoing sentence.
The common theme here is that the word is semantically superfluous. Even obscene expletives seem to have lost their literal significations of describing fecal matter, carnal action, divine punishment and a female dog and only manage to give a vague idea of contemptuousness.
Here Are Examples of Use to Corroborate my Proposal
However, perhaps more convincing than describing that the general concept seems applicable is showing its direct application:
Regarding this use of the word like, I can find some evidence that it has been to as an expletive. Its most particularly associated with a dialect sometimes referred to as valspeak, which is characteristic of teenage Southern Californian girls in the 80s and spread through popular media until the late 90s.
Discourse marker is perhaps the most common name suggested for its
seemingly empty meaning and for its discourse-organizational roles, such
as actually, oh, well, like, I mean, whatever, and you know (Schiffrin 1987,Jucker & Ziv 1998). Traditionally, some of the elements considered as
discourse markers were treated as fillers or expletives, that is, elements
that do not have their own meaning or function.
The Social Meaning of Discourse Markers in Valspeak: Like and Totally by Kyung-Hee Suh
For those of you who prefer a little more authority, the American Heritage Dictionary of the English Language (A.H.D.E.L.), first edition, seventh printing (©1971), directly refers to "like2" as an expletive while exemplifying a sentence very similar to your own:
- Nonstandard Used as an expletive to provide an emphasis or pause: He was like over the hill before he saw the other car. The accident was like horrible.
I can not provide a direct link to this dictionary, but this source seems to be referenced in Teen Talk The Language of Adolescents, which was written by by Sali A. Tagliamonte:
Moreover, The American Heritage Dictionary1[sic] cites the non-standard use of like as an "expletive to provide emphasis or pause."
If you trust neither report of A.H.D.E.L's. contents, then perhaps you can check out the book yourself: The Standard Book Number for the thumb indexed version I used is 395-09066 and the Library of Congress Catalog Card Number is 76-86995.
A few more examples of this usage are provided as examples of an action to avoid in Understanding and Using Good Grammar: Reproducible Lessons, Exercises, and Tests By Genevieve Walberg Schaefer
Avoid Colloquial Uses of Like
Omit like as an expletive to provide a pause: The accident was
Make corrections in the following:
The class was
like boring. The Tennis Match was like exhausting.
The suggestion is
like really weird.
His reaction was
like wild. Like this practice should end.
I would be more comfortable if I could find usages dating farther back than the first edition of A.D.E.L., but it is doubtful one could exist because that probably marks the first time the usage became noteworthy. I can not find reference to it in the main body of Webster's Third New International Dictionary from 1961, and The Online Etymology Dictionary only dates similar emphatic use it back to 1950 "('going, like, really fast')".
Regarding Its Categorization within The Parts of Speech
As a disclaimer I probably should not go into too much detail regarding this, since I consider syntax to be as mysterious as The Wizard of Oz, and have not yet bothered to pay much mind to the behind the curtain. However, I have made a few relevant observations worth some consideration:
This probably is not a conjunction. I did see reference to a contentious usage of like as a conjunction in a few editions of A.H.D.E.L. Understanding and Using Good Grammar classifies it as a subordinator of sorts, which is similar. However, in both of these cases the word like is interchangeable with the terms As, As If or As Though. I do not think any of those suggested substitutions work in these sentences. Moreover, Understanding and Using Good Grammar demonstrates that the word can be cleanly removed, which is not true of the usual conjunctions.
As an expletive, A.H.D.E.L. and the Columbia Guide to Standard American English categorize the word as an adverb. I do not understand why, but I suppose it might be because they consider the word as modifying the whole sentence. A.D.E.L's. suggestion that the word is used for emphatic effect, which I find especially evident in phrases such as "Like, duh!" When used for emphatic effect, it may be considered as an intensifier.
However, I think the provided definition and usual vocal inflections suggests an emotive purpose for the word. When it is combined the fact that it can be so easily removed from the sentence, and the suggestion that expletives are exclamatory in nature, BillJ's suggestion that it is an interjection does not seem unreasonable, considering this definition of the term from An Improved Grammar of the English Language by Noah Webster:
Exclamations are sounds uttered to express passions and emotions; usually those which are violent or sudden. They are called interjections, words thrown in between the parts of a sentence. But this is not always the fact, and the name is insignificant. The more appropriate name is exclamations; as they are mere irregular sounds, uttered as passion dictates, and not subject to rules.