GM is right, of course, but also if I could just say we don't often see the term when speaking about the English language unless it is to discuss the interesting phenomenon of adjectives which are ONLY found as predicate adjectives, such as "asleep" or "abroad" (just about all such words begin with "a.")
By pointing out that "asleep" is a predicate adjective, many people mean that one could something like "The dog is asleep," but you can't say something like "I saw an asleep dog," unlike most adjectives, which can be used both ways, meaning that both "The dog is big" and "I saw a big dog" are correct.
So this is just to say that in contexts wider than just speaking about English, such as the discussion of Latin, GM's more specific definition is often used, but in discussion of English grammar, it's likely that a person using the term "predicate adjective" is talking about adjectives that can ONLY be used this way.