Webster’s Revised Unabridged Dictionary · 1913
Stemma
Stem′ma (·mȧ), n.; pl. Stemmata (#). [NL., fr. Gr. στέμμα, pl. στέμματα, a garland or chaplet.] (Zoöl.) (a) One of the ocelli of an insect. See Ocellus. (b) One of the facets of a compound eye of any arthropod.