/duy as"tl ee', -tl ee/ , n.
1. Physiol. the normal rhythmical dilatation of the heart during which the chambers are filling with blood. Cf. systole (def. 1).
2. Pros. the lengthening of a syllable regularly short, esp. before a pause or at the ictus.
[ 1570-80; diastole diastolé a putting asunder, dilation, lengthening; cf. diastéllein to set apart, equiv. to dia- DIA- + stéllein to put, place ]