subtleyoudaoicibaDictYouDict[subtle 词源字典]
subtle: [14] Latin subtīlis, the ultimate source of English subtle, seems to have originated as a weaving term. It probably goes back ultimately to the phrase sub tēla ‘beneath the lengthwise threads in a loom’ (tēla, source of English toilet and toils, was a contraction of *texla, a relative of English textile). As this was lexicalized via *subtēlis to subtīlis, it developed the meaning ‘finely woven’, which subsequently broadened out to ‘fine, thin’. By the time it reached English, via Old French sutil, it had evolved further, to ‘making fine discriminations’.
=> textile, toilet[subtle etymology, subtle origin, 英语词源]
subtle (adj.)youdaoicibaDictYouDict
c. 1300 (mid-13c. as a surname), sotil, "penetrating; ingenious; refined" (of the mind); "sophisticated, intricate, abstruse" (of arguments), from Old French sotil, soutil, subtil "adept, adroit; cunning, wise; detailed; well-crafted" (12c., Modern French subtil), from Latin subtilis "fine, thin, delicate, finely woven;" figuratively "precise, exact, accurate," in taste or judgment, "fine, keen," of style, "plain, simple, direct," from sub "under" (see sub-) + -tilis, from tela "web, net, warp of a fabric" (see texture (n.)).

From early 14c. in reference to things, "of thin consistency;" in reference to craftsmen, "cunning, skilled, clever;" Depreciative sense "insidious, treacherously cunning; deceitful" is from mid-14c. Material senses of "not dense or viscous, light; pure; delicate, thin, slender; fine, consisting of small particles" are from late 14c. sotil wares were goods sold in powdered form or finely ground. Partially re-Latinized in spelling, and also by confusion with subtile.