the world > life > the body > external parts of body > limb > arm > [adjective] > armpit (4)
Pertaining or adjacent to the armpit or shoulder.
Zoology and Anatomy. Situated beneath the axilla.
Anatomy and Botany. Of or relating to the axilla (of the human body) or an axil (of a plant); = axillary, adj.; (now rare). In later use also…