a commercial establishment that offers services and facilities related to beauty, health/fitness, and/or relaxation;
e.g. She went to a spa to get a massage and other relaxing treatments.
(noun)
a naturally-occurring spring of water that contains many minerals and is considered to have healing or health-giving properties, or a resort (or some other place) that has such a spring;
e.g. Doctors used to advise bathing in a spa to treat various ailments.
(noun)
a small pool or tub containing hot water that may be aerated, such as by a whirlpool device;
e.g. They found the warm water of the spa to be very relaxing.