When a semicolon is seen in a definition in the dictionary, does it mean "or" or "and"?
Kind of? They're used sort of the same way, but I don't think a dictionary would define them that way.
You use semicolons to connect two independent clauses, which are phrases that could stand alone as sentences, meaning they have a subject and a predicate.
Ex.: I like dogs; cats are cool, too.
Another way to connect two independent clauses is to use the FANBOYS: F or A nd N or B ut O r Y et S o
Ex: I like dogs, and cats are cool too.
Semi colon is one of the signs of other signs that denote the independent a clause like you say--- or /and.
others are but, nor, so, yet etc.
So, it is important to understand the type of sentence.
Unless ones are confident of these basic issues, he or she never be confident of his/her English writing.
Hope it works.