subtle (adj.) Look up subtle at Dictionary.com
c.1300, sutel, soutil, in reference to things, "of thin consistency;" in reference to craftsmen, "skilled, clever," from Old French soutil, from Latin subtilis "fine, thin, delicate, finely woven," from sub "under" (see sub-) + -tilis, from tela "web" and texere "to weave" (see texture). The spelling with -b- reflects confusion with subtile. Most non-material senses were present by late 14c.