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hyperthermia
hyperthyroidism
hypertonic
hypertrophy
hyperventilate
hyperventilation syndrome
hypervitaminosis
hypesthesia
hypethral
hypha
hyphen
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hypn-
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hypersomnia

hy·per·som·ni·a [ hpər sómnee ə ]


noun 
Definition:
 
extreme sleepiness: greater sleepiness than is usual or desirable, including extended nocturnal sleep, unplanned daytime sleep, and an inability to remain awake or alert

[Late 19th century. <hyper- + Latin somnus "sleep"]
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