Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
ectoblast is a noun meaning "the outer germ layer that develops into skin and nervous tissue". It carries one recorded sense.
the outer germ layer that develops into skin and nervous tissue
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 ectoblast come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.