The Collaborative International Dictionary of English v.0.48:

Aponeurosis \Ap`o*neu*ro"sis\, n.; pl. Aponeuroses. [Gr. ?,
   fr. ? to pass into a tendon; ? from + ? to strain the sinews,
   ? sinew, tendon, nerve.] (Anat.)
   Any one of the thicker and denser of the deep fasci[ae] which
   cover, invest, and the terminations and attachments of, many
   muscles. They often differ from tendons only in being flat
   and thin. See Fascia.
   [1913 Webster]