: a twilled fabric with silk warp and worsted filling
: a silk fabric in twill weave dyed black
borrowed from Middle French bombasine, bombazine "cotton fabric, fabric with a cotton weft and another material as warp" (Old French drap bombasin "cotton cloth"), borrowed from Upper Italian (Lombardy) bombasina, corresponding to Tuscan bambagino, derivative (with -ino, -ina-ine entry 1) of bambagia, bambagio "cotton" (borrowed from Middle Greek bambákion, derivative of bámbax, pámbax "cotton"), probably conflated with Latin bombȳcinus "of silk" (Medieval Latin, "of cotton," as neuter noun, "cotton"), pseudo-Greek derivative (with -inos-ine entry 1) of bombyc-, bombyx "silkworm, silk," borrowed from Greek *bómbyx, presumed on the basis of bombýkion "cocoon of a kind of moth, probably Pachypasa otus," of uncertain origin — more at bombast
Though the Latin adjective bombȳcinus is conventionally traced to Greek bombýkinos (as in Oxford Latin Dictionary), the Greek word is not attested until significantly later (Libanius, 4th century c.e.). The documentary record of Greek bómbyx is problematic. Liddell and Scott, A Greek-English Lexikon, give as a source "Arist. HA ap. Ath.7.352f.," but this citation—aside from the fact that section 352, of Athenaeus' Deipnosophistae, following Isaac Casaubon's division of the text, is in Book 8, not Book 7—contains only the word bombyliós, a form taken directly from Aristotle's Historia Animalium. There thus appears to be no evidence for bómbyx, in the sense "silkworm" or "silk" in Greek or Latin earlier than Pliny. Historia Animalium does offer both bombyliós or bombýlios (with the variant reading bombylís) and bombýkion, in a discussion of fabric weaving from thread spun from cocoons (551b13-16 in the Royal Prussian Academy Aristotelis opera): "From one particular large grub, which has as it were horns, and differs from the others, there comes, by a metamorphosis of the grub, first a caterpillar, then the cocoon, then the nekýdalos … Certain women unwind and reel off the cocoons of these creatures, and afterwards weave a fabric with the threads thus unwound; a Coan woman of the name of Pamphila, daughter of Plateus, being credited with the first invention of the fabric" - "ek dé tinos skṓlēkos megálou, hòs ékhei hoîon kérata kaì diaphérei tôn állōn, gínetai prôton mèn metabalóntos toû skṓlēkos kámpē, épeita bombýlios, ek dè toûtou nekýdalos … ek dè toútou toû zṓiou kaì tà bombýkia analýousi tôn gynaikôn tinès anapēnizómenai, kápeita hyphaínousin; prṓtē dè légetai hyphênai en Kôi Pamphílē Pláteō thygátēr." Several aspects of this passage are puzzling: bombýlios (which in other contexts means "buzzing insect, bumblebee") appears to be used for bombýkion by error (unless the original is in fact bombýlios, transferred from the insect sense, and bombýkion is an error, later extrapolated into bómbyx?); both the meaning and etymology of nekýdalos have been a conundrum for centuries (does the word refer to the seemingly dead—nékys—creature inside the cocoon?). As has been pointed out (e.g., by Bertrand Hemmerdinger, "De la méconnaissance de quelques étymologies grecques," Glotta, Band 48, Heft 1/2 , p. 65-66), the cocoons in question are not from the cultivated silkworm, Bombyx mori, but rather from a species of wild moth, probably Pachypasa otus; a garment thus produced was called by Latin authors Coa uestis. As by Pliny's time silk from southern and eastern Asia was known in the Mediterranean world, the name for this locally produced "silk" was easily transferred to the more exotic and higher-quality imported fabric. The origin of bombýkion is obscure, though it seems improbable that it has any connection with Middle Persian pambak "cotton" (pace Frisk, Chantraine, Beekes, and other standard handbooks; see etymology and note at bombast). Hemmerdinger (op. cit.) cites approvingly Isidore of Seville's etymology ("And indeed it is called by this name from the fact that it empties out while it produces thread, so that only air is left in it" - "Appellatus autem hoc nomine ab eo quod evacuetur dum fila generat, et aer solus in eo remaneat"); this appears to be a fanciful allusion to Greek bómbyx "flute" and the bomb- family of onomatopoeic words (see bomb entry 1).