D defs.my
Entry 1 sense Webster, 1913

Heartstring

/(härt"strĭng`)/ · Heart·string · IPA
01 n. A nerve or tendon, supposed to brace and sustain the heart.
  1. 1.
    A nerve or tendon, supposed to brace and sustain the heart.
    “Sobbing, as if a heartstring broke.” Moore.