Emergency Locator Transmitter, a radio beacon mounted in the aircraft usually near the tail, activated by an accelerometer in the event of a crash.  The signal is picked up by low-earth orbiting satellites for use in search and rescue operations. 

(Altitude) Above Ground Level, where all aircraft must fly. Always a positive number, by the way. Distinguished from MSL, (above) Mean Sea Level, which is what an altimeter measures, and can indeed be negative. Cloud levels are given as AGL.

Movable surface on the outboard trailing edge of each wing. Operated by rotating the control wheel (or tilting the stick from side to side), the ailerons control roll (animation).

), corrected for altitude and temperature, becomes 'true airspeed' (TAS).  Thus "truing out" at 150 KTAS with a 15-knot tailwind "makes good" 165 knots "over the ground."  

Alpha, Bravo, Charlie (shar-lee), Delta, Echo, Foxtrot (often shortened to Fox), Golf, Hotel, India, Juliet, Kilo, Lima (pronounced as the city not the bean), Mike, November, Oscar (oss-kah), Papa, Quebec (kay-beck), Romeo, Sierra, Tango, Uniform (oo-nee-form), Victor (vik-tah), Whiskey, X-ray, Yankee, Zulu. Use these in casual conversation anywher [..]

Aircraft Owners and Pilots Association, non-profit political organization serving the interests of its members to promote the economy, safety, utility, and popularity of flight in general aviation aircraft.

An ironic aerodynamic property for minimizing drag in high-speed aircraft.   

or Attitude Indicator, an instrument symbolizing the aircraft in the center, and the background controlled by a gyro.

Automatic Terminal Information Service (pronounced ATE-is), a transcribed radio message that gives up-to-date advisories about conditions and procedures at a particular airport. The pilot listens to the message on the ground before taxiing and in the air before approaching the airport.  

In aviation, the expression 'unusual attitudes' has a special meaning. Just so you know, it has nothing to do with extraordinary mental states or peculiar dispositions. 'Attitude' is the general term used to describe (ahem) the instantaneous angular position of the airplane with respect to the horizon.