CQD

CQD or cqd can be

 Carbon quantum dot, a carbon nanoparticle which is less than 10 nm in size and have some form of surface passivation
CQD (distress signal), one of the first distress signals that started being used in regard to radio signals
 Chuanqiandian Cluster Miao language (ISO 639-3: cqd), a Hmongic language spoken by the Hmong people
 Shahrekord Shahid Estaki International Airport (IATA: CQD), an airport in Shahrekord, Chaharmahal & Bakhtiari, Iran