- ACOS stands for Arc Cosine (Inverse Cosine)
- ACOS stands for American College of Surgeons
- ACOS stands for Asthma-COPD (Chronic Obstructive Pulmonary Disease) Overlap Syndrome
- ACOS stands for Assistant Chief of Staff (also seen as A/COS)
- ACOS stands for Advanced Core Operating System
- ACOS stands for Associate Chief of Staff
- ACOS stands for American College of Osteopathic Surgeons
- ACOS stands for Advisory Committee on Safety (IEC)
- ACOS stands for A Change of Seasons (Dream Theater album)
- ACOS stands for A Crown of Swords (Wheel of Time; book 7)
- ACOS stands for Air and Space Communications Operations Squadron (US Air Force)
- ACOS stands for Australian Chamber Of Shipping
- ACOS stands for Associazione Cattolica Operatori Sanitari (Italian: Catholic Association of Medics and Paramedics)
ACOS