2482 A lie consists in speaking a falsehood with the the intention of deceiving. The Lord denounces lying as the work of the devil: 'You are of your father the devil ... there is no truth in him. When he lies, he speaks according to his own nature, for he is a liar and the father of lies." [Ellipsis is in the original.]
2483 Lying is the most direct offence against the truth. To lie is to speak or act against the truth in order to lead someone into error. By injuring man's relation to truth and to his neighbour, a lie offends against the fundamental relation of man and of his word to the Lord.
There is a surface contradiction worth noting here. 2482 ties lying to what logicians call statements. Presumably it includes written as well as spoken statements although only speaking is mentioned here. This ties lying to strict issues of truth in a logical sense.
Somewhere along the line it must have occurred to the moral theologians behind the catechism that that would not do. So 2483 tells us that lying can mean either speaking or acting against the truth.
My first thought is that this outlaws a while lot of games. Bluffing at poker, for example, would be right out as it is very much a case of speaking and acting to deceive others. So would halfbacks faking left when they mean to go right as that is clearly a case of acting so as to lead someone into error. Gambling is okay according to 2413 so long as we don't cheat or deprive others of what they really need by doing so. But you can't play these games at all according to 2482 and 2483.
Now I know some people will say, your just playing games yourself here but I'm not. There are a lot of human activities where deceiving someone is quite acceptable (defense attorneys in a court of law are not obliged to call attention to possible errors in the testimony of their witnesses) and this definition is far too broad.