Ibṭ: (Arabic: underarm/armpit, pl. bītān, synonym: bāt, tkhrāṣah, tnfāyah/tnfājah), gusset, a triangular or rhomboidal piece of fabric inserted into the seam to add breadth or reduce stress from tight-fitting clothing. Used for underarms on tunic dresses, side sleeve panels on overgarments (thāwb), and undergarments (ṣarāwl).