a patient who pays for treatment rather than receiving it free or under subsidy from the State or a public body.

a person receiving treatment from a doctor under the National Insurance Acts of 1911 (amended 1913) (see sense 14c).

a person under medical care for a mental illness; a psychiatric patient.

With distinguishing word. An individual who metabolizes and inactivates a drug, spec. the antibiotic isoniazid, at the specified rate. Cf. metabolizer…

A person permanently dependent upon a ventilator (artificial respirator) to maintain breathing.

U.S. Among members of the medical profession: a difficult or disagreeable patient, esp. an elderly one.