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.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.