There is a list of these on the English Wikipedia. Here's the ones I remember having seen in Fifa 14. They are always color-coded to show which area of the game they belong to. For the center positions the left and right seems to refer to the current formation. I.e. a player cannot be a LCB. He's a CB on his bio, but he is playing the LCB position.
Goalkeeper: Orange
GK: Goalkeeper
Defense: Yellow
CB: Center-backLCB: Left center-backRCB: Right center-backLB: Left-back (Full-back)RB: Right-back (Full-back)
Midfield: Green
CM: Centre midfieldLDM: Left center midfieldLAM: Left attacking midfieldRDM: Right center midfieldRAM: Right attacking midfieldCDM: Centre defensive midfieldCAM: Centre attacking midfieldLM: Left midfieldRM: Right midfield
Attack: Blue
ST: StrikerCF: Center forwardLW: Left wingerRW: Right winger
