The prefix hypo- means under, too little or reduced. Hypotension is low blood pressure, hypoglycaemia low blood sugar, hypothyroidism an underactive thyroid. Its counterpart is hyper-.
Greek hypó = under, below
under-, reduced
hypo-
Besides quantity, hypo- also has a spatial meaning: the hypothalamus lies below the thalamus, the hypophysis below the brain.
So the same prefix can describe either an amount or a position, depending on the word stem – a typical example of why terminology needs context.
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