Coa may refer to:
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams.
Coagulation (also known as clotting) is the process by which blood changes from a liquid to a gel, forming a blood clot.
Coaxial cable, or coax (pronounced /ˈkoʊ.æks/), is a type of cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield.
Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content, and, since the 1880s, has been widely used to generate electricity.
A coat of arms is a unique heraldic design on an escutcheon (i.e. shield), surcoat, or tabard. The coat of arms on an escutcheon forms the central element of the full heraldic achievement which consists of shield, supporters, crest, and motto.
The Coachella Valley Music and Arts Festival (commonly referred to as Coachella or the Coachella Festival) is an annual music and arts festival held at the Empire Polo Club in Indio, California, located in the Inland Empire's Coachella Valley, in the Colorado Desert.
The Coachella Valley (/koʊˈtʃɛlə/, /koʊ.əˈtʃɛlə/) is a desert valley in Southern California which extends for approximately 45 mi (72 km) in Riverside County southeast from the San Bernardino Mountains to the northern shore of the Salton Sea.
Coaching is a form of development in which a person called a coach supports a learner or client in achieving a specific personal or professional goal by providing training, advice and guidance.
Coastal management is defense against flooding and erosion, and techniques that stop erosion to claim lands.