सूत्र [ sūtra ] [ sū́tra ] n. (accord. to g. [ ardhacādi ] also m. ; fr. √ [ siv ] , " to sew " , and connected with [ sūci ] and [ sūnā ] ) a thread , yarn , string , line , cord , wire Lit. AV.

  a measuring line ( cf. [ -pāta ] ) Lit. Hariv. Lit. VarBṛS.

  the sacred thread or cord worn by the first three classes ( cf. [ yajñopavīta ] ) Lit. BhP.

  a girdle Lit. ib.

  a fibre Lit. Kālid.

  a line , stroke Lit. MBh. Lit. VarBṛS. Lit. Gol.

  a sketch , plan Lit. Rājat.

  that which like a thread runs through or holds together everything , rule , direction Lit. BhP.

  a short sentence or aphoristic rule , and any work or manual consisting of strings of such rules hanging together like threads (these Sūtra works form manuals of teaching in ritual , philosophy , grammar : e.g. in ritual there are first the Śrauta-sūtras , and among them the Kalpa-sūtras , founded directly on Śruti q.v. ; they form a kind of rubric to Vedic ceremonial , giving concise rules for the performance of every kind of sacrifice ( Lit. IW. 146 ) ; other kinds of Śruti works are the Gṛihya-sūtras and Sāmayācārika or Dharma-sūtras i.e. " rules for domestic ceremonies and conventional customs " , sometimes called collectively Smārta-sūtras ( as founded on [ smṛti ] or " tradition " see [ smārta ] ) ; these led to the later Dharmaśāstras or " law-books " ( Lit. IW. 145 ) ; in philosophy each system has its regular text-book of aphorisms written in Sūtras by its supposed founder ( Lit. IW. 60 ) ; in Vyākaraṇa or grammar there are the celebrated Sūtras of Pāṇini in eight books , which are the groundwork of a vast grammatical literature ; with Buddhists , Pāśupatas the term Sūtra is applied to original text books as opp. to explanatory works ; with Jainas they form part of the Dṛishṭivāda) Lit. IW. 162

  a kind of tree Lit. DivyA7v.