Is there a term that I can use to generically refer to a word, an idiom or any other kind of linguistic entity related to vocabulary? vocabulary unit is what I can conceive of at the moment. Does that sound okay to you people? To my ears, it sounds someway okay but, at the same time, it reminds me of an English grammar textbook that has chapters, often called units, dedicated to learning vocabulary.
A technical term for this is LEXICAL ITEM. Linguists often refer to words as lexemes. However, lexeme would not work for the Original Poster's needs because it would not cover idioms, or, for example phrasal verbs. These entail more than one lexeme, more than one word.
We often use the uncountable noun lexis to refer to vocabulary in general.
Hope this is helpful!
I wonder if we're over-complicating things here for the OP? Given the context - we're simply looking for an entry or term referenced in a list.
I prefer term as it's a little more specific.
From the OED:
Any word or group of words expressing a notion or conception, or denoting an object of thought; an expression (for something).