The sutras, because they tally with the mind of man and the laws of nature.

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous

契經(sūtra). Scripture.

sūtra

(Skt; Pāli, sutta, a thread). A discourse of the Buddha. In the Pāli Canon these texts are grouped together in the second of the three ‘baskets’ (piṭaka) or divisions of the teachings, namely the Sūtra Piṭaka. This in turn is divided into five collections known as Nikāyas (Āgamas in Sanskrit), in which the suttas are grouped in order of length. These early discourses are all attributed to the historical Buddha, Siddhartha Gautama. The Mahāyāna canonical collection of sūtras is more extensive and includes many lengthy independent works. While the historical Buddha is plainly not the author of these works, they are regarded by followers of the Mahāyānas as of no less, and perhaps greater importance, than the earlier texts. Many, such as the Lotus Sūtra and the Laṇkāvatāra Sūtra, became the foundational scriptures of new schools of Buddhism. The tradition of composing sūtras continued for many centuries during the medieval period. Most of these were composed in Sanskrit but many now survive only in Tibetan or Chinese translation. Sometimes independent works were amalgamated into more extensive ones known as vaipūlya sūtras.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)

修他羅  A transcription of the Sanskrit sūtra.

蘇呾纜  A transliteration of the Sanskrit sūtra.

Sūtra. In later Indian literature, the term, a Sanskrit one, which means "thread" (possibly derived from siv, to sew, and alluding to the stitching together of the manuscript leaves), is used of certain compositions written in an aphoritic style. The earliest examples are legal manuals. Later still emerged the manu-smṛti, written in a freer and more expanded style and in metre, being therefore more easily committed to memory. Almost all Indian philosophical systems adopted the terse, sūtra form, necessitating commentaries among which the Brahma-sutra is one of the best known. The Pali counterpart is sutta.

Geddes MacGregor, Dictionary of Religion and Philosophy, New York: Paragon House, 1989

Sūtra  經  It is a "path" necessarily passed through in the cultivation of the Way.

漢英-英漢-英英佛學辭典字庫

(1) A discourse by the Buddha. (2) A concise discourse; the first of the dvādaśāṅga-dharma-pravacana.

Sarvastivada Abhidharma, Sanskrit-English Glossary, by Bhikkhu KL Dhammajoti

sū́tra n. (accord. to g. ardhacâdi also m
• fr. √siv, 'to sew', and connected with sūci and sūnā) a thread, yarn, string, line, cord, wire AV. &c. &c
• a measuring line (cf. -pāta) Hariv. VarBṛS. &c
• the sacred thread or cord worn by the first three classes (cf. yajñôpaviita) BhP
• a girdle ib
• a fibre Kālid
• a line, stroke MBh. VarBṛS. Gol
• a sketch, plan Rājat
• that which like a thread runs through or holds together everything, rule, direction 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 &c.: e.g. in ritual there are first the Śrauta-sûtras, and among them the Kalpa-sûtras, 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 [IW. 146 &c.] ; 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', smārta] ; these led to the later Dharmaśāstras or 'law-books' īW. 145 ; in philosophy each system has its regular text-book of aphorisms written in Sūtras by its supposed founder [IW. 60 &c.] ; 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 &c. the term Sūtra is applied to original text books as opp. to explanatory works ; with Jainas they form part of the Dṛishṭivāda) IW. 162 &c
• a kind of tree Divyâv

Sanskrit-English Dictionary, by M. Monier William

mdo

[translation-san] {MSA,MV} sūtra

[translation-san] {MSA} sūtrānta

[translation-san] {C} saṃkṣipteṇa

[translation-eng] {Hopkins} sūtra; discourse; short sentence; axiom; scripture

[translation-eng] {C} sets of discourses; in short; briefly; to cut it short

Jeffrey Hopkins' Tibetan-Sanskrit-English Dictionary