noun

• (chiefly uncountable, physiology) The phase or process of relaxation and dilation of the heart chambers, between contractions, during which they fill with blood; an instance of the process.
• (uncountable, prosody) The lengthening of a vowel or syllable beyond its typical length.
• (Greek grammar) The hypodiastole, a textual or punctuation mark formerly used to disambiguate homonyms in Greek.