Kāṣāya (Sanskrit: काषाय kāṣāya; Pali: kasāva; Chinese: 袈裟; pinyin: jiāshā; Cantonese Jyutping: gaa¹saa¹ ; Japanese: 袈裟 kesa; Korean: 袈裟 가사 gasa; Vietnamese: cà-sa), "chougu" (Tibetan) are the robes of Buddhist monks and nuns, named after a brown or saffron dye. In Sanskrit and Pali, these robes are also given the more general term cīvara, which references the robes without regard to color.

Buddhist kāṣāya are said to have originated in India as set of robes for the devotees of Gautama Buddha. A notable variant has a pattern reminiscent of an Asian rice field. Original kāṣāya were constructed of discarded fabric. These were stitched together to form three rectangular pieces of cloth, which were then fit over the body in a specific manner. The three main pieces of cloth are the antarvāsa, the uttarāsaṇga, and the saṃghāti. Together they form the "triple robe," or tricīvara. The tricīvara is described more fully in the Theravāda Vinaya (Vin 1:94 289).

The antarvāsa is the inner robe covering the lower body. It is the undergarment that flows underneath the other layers of clothing. It has a large neck, and almost entirely covers the torso. In representations of the Buddha, the bottom of the antarvāsa usually protrudes, and appears in the rough shape of a triangle.