Dear friends,
Without wishing to prolong too much what has already been a very long (though highly informative!) thread (so to speak), I thought that this might be of some interest:
In the early 9th century Tibetan work, the “Two-Volume Lexicon” (sgra sbyor bam po gnyis pa), which was compiled by a team of Tibetan translators working under the guidance of a group of monastic scholars from Aparântaka
(Kashmir/Gandhâra/Bactria) and provides
nirukta-style explanations of several hundred key terms in Sanskrit with Tibetan commentary, sûtra is glossed
arthasûcanâd sûtra
[read, of course, arthasûcanât
sûtram].
Once more, SÛC, and nothing to do with thread, was prominent in the Buddhist understanding of the term.