Wikipedia
Airman basic (AB) is the lowest enlisted rank in the United States Air Force (USAF), immediately below airman. The pay grade for airman basic is E-1.
As opposed to all other USAF enlisted and officer ranks, airman basic has no rank insignia affiliated. The lack of uniform insignia for airmen basic is the reason for the nickname "slick-sleeve"; all other enlisted Air Force ranks wear stripes and chevrons on their uniform sleeves.
In accordance with Air Force Instruction (AFI) 36-2618, The Enlisted Force Structure, the term of address for an airman basic is "Airman Basic" or "Airman".
Usage examples of "airman basic".
Aces High was going to war, and every man and woman in the small unit, from the airman basic cook in the in-flight kitchen to the commander, knew it.
Having risen through the ranks from airman basic to three-star general over his thirty-year career, Samson's entire life had been a series of challenges and successes.