Calefacient is a now obsolete medical term that means
making or tending to make anything hot or warm. It also
refers to something that causes a sense of warmth or
heat in the body part that it is placed on. An example
would be a hot water bottle warming the back.
Calefacient could be used to refer to the warming
effects of mustard paste, which is a soft moist mass of
mustard seed spread on a cloth that is applied (not the
actual mustard seed but the cloth) to the chest or back
to treat bronchial pneumonia or pleurisy. Pleurisy is
swelling and irritation of the pleura. The pleura is the
smooth, moist double layer of flexible tissue that lines
the lungs and the chest wall. Pneumonia is inflammation
of the lungs due to infection.
A hot water bottle is calefacient.
If calefacient was still used in modern times it could be used to describe the warming
feeling of medicated creams commonly sold in stores to treat painful conditions. It could
also be used to describe cauterization, in which part of the body is burned to remove or
close part of it for medical healing purposes (e.g., to stop severe blood loss and close
Calefacient comes from the Latin word “calefacere” meaning “to heat.”