What does paracalor mean in Greek?

There is no Greek word "paracalor." There's no direct translation or combination of Greek roots that would yield that word. It's likely a modern coinage, possibly combining elements from Greek roots related to heat (like *thermos*) or a prefix like *para-* (meaning "beside," "beyond," or "against") with a Latin or another root. Without further context on where you encountered this word, it's impossible to say what its intended meaning might be.