"Seems like an overkill" vs. "seems like overkill" [closed]

I’m wondering if an article is used with the word overkill:

• Something seems like an overkill (to me).
• Something seems like overkill (to me).

Which is grammatical?

It depends what is meant by overkill.

ODO has overkill as a mass (uncountable) noun:

noun [mass noun]
1 excessive use, treatment, or action
2 the amount by which destruction or the capacity for destruction exceeds what is necessary

[Interestingly, OED indicates sense 2 came first, and the word has been applied more generally so that sense 1 is now what overkill usually means.]

Because it's a mass noun, overkill will not usually take the indefinite article.

Mass nouns can take the indefinite article when you are talking about a type of the thing: "Foccaccia is a bread". However it's difficult to conceive a sentence where overkill would fit like that.