\Con"cha\, n. [LL. (in sense 1), fr. ? concha. See
{Conch}.]
1. (Arch.) The plain semidome of an apse; sometimes used for
   the entire apse.
2. (Anat.) The external ear; esp. the largest and deepest
   concavity of the external ear, surrounding the entrance to
   the auditory canal.