basal body temperature
Medical Definition of basal body temperature
: the temperature of the body at rest that is typically taken immediately after waking from sleep ◆The basal body temperature of a woman slightly rises during ovulation and may be tracked to estimate when future ovulation will occur. <When she ovulates, her basal body temperature rises about one degree and remains elevated until her next period.—Jane E. Brody, The New York Times, 1 Jan. 2002>
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