/ daɪˈæstəli; NAmE / noun
( medical ) the stage of the heart's rhythm when its muscles relax and the heart fills with blood
—compare systole
► dia·stol·ic / ˌdaɪəˈstɒlɪk; NAmE -ˈstɑːl-/ adjective
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WORD ORIGIN
late 16th cent.: via late Latin from Greek , separation, expansion , from diastellein , from dia apart + stellein to place.