mes·ectoderm \(ˈ)me]z, (ˈ)mē], ]s+\noun Etymology:mesoderm + ectoderm : an embryonic blastomere or cell layer not yet differentiated into mesoderm and ectoderm but destined to give rise to both • mes·ectodermaladjective • mes·ectodermic\|me]z, |mē], ]s+\adjective