noun, feminine/ˈdjastole/plural: diástoles
diástole is feminine in Spanish.
diastole (period when the heart refills with blood); diastole (lengthening of a syllable)
Ultimately from Ancient Greek διαστολή (diastolḗ, “separation, drawing asunder”), from διά (diá, “apart”) + στέλλειν (stéllein, “send”).