360, 540, etc.
Number describing degrees in an arc. A 360 represents one full turn through an axis. A 360 turn, for example, is a flat turn where the aircraft does not roll its wings but rather just 'slides' through 360 degrees turning on rudder only. For helis: A 540 stall turn, for example, describes a one and one half revolution spin at the apex of a vertical stall, which results in the helicopter resuming nose forward flight before recovery.

3D
Term describing a type of flight pattern, which is characterized by the performance of very specialized aerobatic manuevers below the model's normal stall speed. Examples include torque rolls, 'walk in the park', harriers, hangers, etc. For helis: combining two or more maneuvers into one maneuver. Examples: rolling circle, inverted backwards loop.

3F
Slang abbreviation for flip flop flying. Similar to 3D, but without the finesse.