CAAS stands for;

CAAS Civil Aviation Authority of Singapore
CaaS Communications-as-a-Service (outsourcing model for enterprise communications)
CAAS Classical Association of the Atlantic States (est. 1907)

CAAS Commission on Accreditation of Ambulance Services
CAAS Common Avionics Architecture System
CAAS Crimeware as a Service (computing)
CAAS Center for Alcohol and Addiction Studies
CAAS Cognition-as-a-Service
CAAS Chet Atkins Appreciation Society (Nashville, TN)
CAAS Chinese Academy of Agricultural Science
CAAS Central Arkansas Astronomical Society
CAAS Cardiovascular Angiography Analysis System
CaaS Compiler-as-a-Service

CAAS Canadian Association of African Studies
CAAS Centre for Academic and Administrative Studies (India)
CaaS Compute-as-a-Service (Verizon)
CAAS Criticality Accident Alarm System (nuclear)
CAAS Center for Afro-American and African Studies
CAAS Contractor Advisory and Assistance Services
CAAS Cruise Agent Accreditation Scheme (PSARA; United Kingdom)
CAAS Common Aviation Architecture System (US DoD)
CAAS Contract Advisory Assistance Services
CAAS Chloride Aqueous Actinide Separation

CAAS Commercial Activity Automated System
CAAS Community Accounting Aid Service
CAAS Contractor Assistance and Advisory Service
CAAS Computer-Aided Assessment System
CAAS Common Authentication and Authorization Service
CAAS Changi Aviation Authority of Singapore
CAAS Combined Artillery/Aviation Simulator
CAAS Computer Apathy and Anxiety Scale
CAAS Combined Arms And Support
CAAS Chemical Agent Alarm System
CaaS Classroom as a Service (trademark of VisiLearn, LLC)