1. Physiology The normal rhythmically occurring relaxation and dilatation of the heart chambers, especially the ventricles, during which they fill with blood.
2. The lengthening of a normally short syllable in Greek and Latin verse.
[Greek diastolē, dilation, separation, from diastellein, to expand : dia-, apart; see DIA- + stellein, to place, send; see stel- in the Appendix of Indo-European roots.]
di′as·tolic (dī′ə-stŏlĭk) adj.
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