NCIt definition : The smallest subdivisions of the bronchial tree, which are both acartilagenous and
aglandular.;
Alternative definition : NCI-GLOSS: A tiny branch of air tubes in the lungs.; UBERON: The conducting airway of the lungs found terminal to the bronchi; these structures
contain neither cartilage nor mucous-secreting glands; the epithelium of the bronchioles
becomes thinner with each branching.;