Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
heartsick is an adjective meaning "full of sorrow". It carries 2 recorded senses.
full of sorrow
without or almost without hope
“despondent about his failure”
“too heartsick to fight back”
Definitions, synonyms and semantic relations for heartsick come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.