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-back
- LCB: Left center-back
- RCB: Right center-back
- LB: Left-back (Full-back)
- RB: Right-back (Full-back)
Midfield: Green
- CM : Centre midfield
- LDM: Left centerdefensive midfield
- LAM: Left attacking midfield
- RDM: Right centerdefensive midfield
- RAM: Right attacking midfield
- CDM: Centre defensive midfield
- CAM: Centre attacking midfield
- LM : Left midfield
- RM : Right midfield
Attack: Blue
- ST: Striker
- CF: Center forward
- LW: Left winger
- RW: Right winger