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PALLIATIVE

A medicine or treatment that is given to effect some relief from symptoms, if only temporarily, but does not cure the ailment.  This is often the case in the treatment of cancer.

PARASITE

Any organism that obtains its nutrients by living in or on the body of another organism (the host).  The extent to which the host is damaged by the parasite ranges from virtually no effect to, in extreme cases, death.  Parasites in humans include worms, viruses, fungi, etc.

PATHOGEN

The term applied to an organism that causes disease. Most pathogens affecting humans are bacteria and viruses.

PREMENSTRUAL SYNDROME

The occurrence for up to ten days before menstruation, of such symptoms as headache, nervousness and irritability, emotional disturbance, depression, fatigue with other physical manifestations such as swelling of legs, breasts and constipation.  The condition usually disappears soon after menstruation begins.  The cause is not known although the hormone progesterone is probably involved in some way.