Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
nasion is a noun meaning "the craniometric point at the bridge of the nose where the frontal and nasal bones of the skull meet". It carries one recorded sense.
the craniometric point at the bridge of the nose where the frontal and nasal bones of the skull meet
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for nasion come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.