Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
heliacal is an adjective meaning "pertaining to or near the sun; especially the first rising of a star after and last setting before its invisibility owing to its conjunction with the sun". It carries one recorded sense.
pertaining to or near the sun; especially the first rising of a star after and last setting before its invisibility owing to its conjunction with the sun
“the heliacal rising of the Dog Star”
“the heliacal or Sothic year is determined by the heliacal rising of Sothis (the Egyptian name for the Dog Star)”
Definitions, synonyms and semantic relations for heliacal come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.