Abbreviation: AF-S = "Autofocus-Silent" (Nikon)
The abbreviation AF-S means "Autofocus-Silent" and is seen on Nikon products.
Explanation from Nikon
The lens uses a ”Silent Wave Motor” (ultrasonic motor) to focus quietly and quickly. Similar to Canon´s ”USM” technology. Introduced in 1996.
See examples of effected products
 | Nikon AF-S 105mm F2.8 G IF-ED Micro-Nikkor VR |
 | Nikon AF-S 14-24mm F2.8 G ED |
 | Nikon AF-S 70-200mm F2.8 G IF-ED VR II |