Μαλακία xD
("μαλακια" (NOT a polite word) means many things, depending on the context. Usualy means something stupidly bad (έκανα μαλακία = I did malakia = I did something stupid). The original meaning of the word has to do with masturbation (τράβηξα μαλακία = i jerked off). That's where the "μαλάκας" comes from, originaly it means that the person jerks off and does stupid things because of it.)
While it's true the greek vocabulary is very very ritch, pool doesn't have many greek words...
I honestly don't know where the word "billiards" came from, but I have to say that in greek it is μπιλιάρδο (billiardo) and μπίλια (billia) in greek is a small ball, usually it refears to a marble, but many people call billiard balls μπίλια (or μπίλιες = plural).