dīˈastə(ˌ)lē, -ˈaas-, -_li noun
( -s )
Etymology: Greek diastolē dilatation, from diastellein to expand, be dilated, from dia- + stellein to make ready, start out, send — more at stall
1.
a. : the passive rhythmical expansion or dilatation of the cavities of the heart during which they fill with blood — compare systole
b. : the rhythmical expansion of a pulsating vacuole
2. prosody : a lengthening of a short quantity or syllable
3. : expansion