Medical Definition of threshold
: the point at which a physiological or psychological effect begins to be produced (as the degree of stimulation of a nerve which just produces a response or the concentration of sugar in the blood at which sugar just begins to pass the barrier of the kidneys and enter the urine) <below the threshold of consciousness> <the threshold of pain> <a high renal clearance threshold>—called also
Seen and Heard
What made you want to look up threshold? Please tell us where you read or heard it (including the quote, if possible).