(n.) The hollow beneath the junction of the arm and shoulder; the axilla.

alveolar ridge alveolation antrum apex armpit arytenoid cartilages back basin blade bowl cavity concave concavity crater crypt cup dent depression dimple dint dip dorsum fold follicle funnel chest furrow gouge hard palate hole hollow hollow shell honeycomb impress impression imprint indent indentation indention indenture lacuna larynx lips nasal cavity notch oral cavity palate pharyngeal cavity pharynx pit pock pocket pockmark print punch bowl scoop shell sink sinus socket soft palate speech organ sunken part syrinx teeth teeth ridge tip tongue trough velum vocal chink vocal cords vocal folds vocal processes voice box vug