Dry mouth: The condition of not having enough saliva to keep the mouth wet. This is due to inadequate function of the salivary glands. Everyone has dry mouth once in a while when they are nervous, upset or under stress. But if someone has a dry mouth most all of the time, it can be uncomfortable and lead to serious health problems.

Dry mouth can cause difficulties in tasting, chewing, swallowing, and speaking. If it goes untreated, severe dry mouth can also lead to increased levels of tooth decay and infections of the mouth such as thrush. Severe dry mouth is not a normal part of aging. It can be a clue to systemic diseases such as Sjogren syndrome, systemic lupus erythematosus, rheumatoid arthritis, scleroderma, sarcoidosis, amyloidosis, and hypothyroidism. Some medications can also cause dry mouth.

Dry mouth is medically termed xerostomia. From the Greek "xeros" (dry) + "stoma" (mouth).