Chams normally come part of game Direct3D or OpenGL hacks. Chams are like wallhacks but with an added bonus. Eg: When the opposition players are in front of walls or obejects, they would appear red. When they're behind it, they're green.
DLL injection is a technique used for running code within the address space of another process by forcing it to load a dynamic-link library. DLL injection is often used by external programs to influence the behavior of another program in a way its authors did not anticipate or intend. For example, the injected code could hook system function calls, or read the contents of password textboxes, which cannot be done the usual way. A program used to inject arbitrary code into arbitrary processes is called a DLL injector.
Game trainers are programs made to modify memory of a computer game thereby modifying its behavior using addresses and values, in order to allow cheating. It can "freeze" a memory address disallowing the game from lowering or changing the information stored at that memory address e.g. health meter, ammo counter or manipulate the data at the memory addresses specified to suit the needs of the person cheating at the game.
I have no idea what a "timedtap" is, where did you even find this terminology?