Being able to talk around an unknown word is a good skill to learn and a giant leap forward in terms of conversational fluency. It's not just a matter of talking about concepts that didn't exist in the Classical era, but also something you can use when you simply don't know or have forgotten a word.
For example, you may not know a word for "pencil." You could ask someone. They may know. They may not. A dictionary might be consulted, in which case whatever you were trying to say has to wait. If you've been around Latin-speaking groups long enough, you've been there, done that.
You don't need to "quomodo dicitur" everything. You can say, for instance, "id instrumentum quo scribunt discipuli." Or something to that effect. "Cujus lineae facile delentur," if you need to distinguish it from a pen. When you do that, you're practicing fluent language use. It's not cheating. You do this all day in your native language. When "pencil" is on the tip of your tongue and won't come out, what do you say? "Hand me the uh... the writing thing, yeah, that one."
When you get the chance later on, you can look up the word in a time and setting where pulling out a dictionary won't disrupt the flow of conversation and rob you of a chance to practice talking around unknowns.
For the record, Graphis, graphidis, f. is a decent word for "pencil."