ax·il /ˈæksəl, ˌsɪl/
  葉腋
  Ax·il n.  Bot. The angle or point of divergence between the upper side of a branch, leaf, or petiole, and the stem or branch from which it springs.
  ◄ ►
  axil
       n : the upper angle between an axis and an offshoot such as a
           branch or leafstalk