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]