1. Hindu treatise or treatises on particular topics, amounting to law books or codes. The sūtra manuals of the priests are extended and better organized. The best known examples are the Dharmaśāstras (e.g. Manusmṛti, Yajñavalkyasmṛti), Arthaśāstra, and Kāmaśāstras (e.g. of Vātsyāyana).
2. In Buddhism, Mahāyāna commentaries on philosophical issues in the sūtras.
"Śāstra(s)." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (October 17, 2018). http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/sastras
"Śāstra(s)." The Concise Oxford Dictionary of World Religions. . Retrieved October 17, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/sastras