heartstring

== English == === Etymology === From heart +‎ string. === Noun === heartstring (plural heartstrings) (rare) singular of heartstrings (anatomy, historical) A tendon or other structure resembling a cord once thought to be attached to, or to brace, the heart. (figurative) A source of one's deepest emotions or inner feelings, especially compassion or love. (figurative, archaic) The essential or vital part of something; the core, the essence, the heart. Synonyms: crux, gist; see also Thesaurus:gist