stemma

from WordNet (r) 3.0 (2006)

stemma
    n 1: a tree diagram showing a reconstruction of the transmission
         of manuscripts of a literary work
    2: the descendants of one individual; "his entire lineage has
       been warriors" [syn: {lineage}, {line}, {line of descent},
       {descent}, {bloodline}, {blood line}, {blood}, {pedigree},
       {ancestry}, {origin}, {parentage}, {stemma}, {stock}]
    3: an eye having a single lens [syn: {simple eye}, {stemma},
       {ocellus}]

from The Collaborative International Dictionary of English v.0.48

Stemma \Stem"ma\, n.; pl. {Stemmata}. [NL., fr. Gr. ?, pl. ?, a
   garland or chaplet.] (Zool.)
   (a) One of the ocelli of an insect. See {Ocellus}.
   (b) One of the facets of a compound eye of any arthropod.
       [1913 Webster]