1Cold, chilly; freezing, frozen; frigid.
Originally: †(of a fever) characterized by paroxysms in which the stage of rigor is severe or prolonged; designating such a stage; (obsolete). In later use: (especially of forms of malaria and cholera) characterized by a (frequently terminal) stage in which the patient becomes cold and clammy as a result of hypovolaemic or septicaemic shock; designating this state; (also) having an abnormally low body temperature, especially as a result of shock.
Early 17th century; earliest use found in Henry Cockeram (fl. 1623–1658), lexicographer. From classical Latin algidus cold from algēre to be cold (of unknown origin) + -idus.