Celebrim
Legend
I alwasy understood 'cinematic', at least in the context of rpgs, to mean something like 'modelling the conventions of drama more than modelling the conventions of real life'.
I'm not sure that there is a fixed definition. Alot of the terms bandied around with RPG's end up serving double or triple duty. I've certainly heard 'cinematic' used in that sense, but I never have really thought it very useful used in that way. For one thing, movie/dramatic conventions are not tightly established for fantasy, and certainly not for swords and sorcery, so I'd have a very hard time knowing what was being modeled.
Perhaps you can site for me the dramatic works which set the conventions of fantasy so I'd know what you meant by 'cinematic'.
For my part, I consider the game 'cinematic' (in my sense) if the rules encourage envisioning what the players do. For example, one area of play in D&D that I've always considered poorly cinematic is the attack. In D&D, the attack is abstract, so its up to the DM/player to provide the cinematic description. Very usually, this gets dull and so D&D defaults to, "I attack ... hit... and do 18 damage." This description, which is closely tied to the rules, is not cinematic. By contrast, game systems with called shots, contested active defenses, and tables of outcomes tend to have highly cinematic combat. So one argument for 4e being more cinematic would be, 'The manuevers provide cinematic details." While I think that they can, in practice though, I think the manuevers are abstract enough that in most cases they are simply different sorts of attacks, "I perform manuever X... hit... and 18 damage."