Merriam-Webster Collegiate Dictionary - diaphanous

 adjective  Etymology: Medieval Latin diaphanus, from Greek diaphanes, from diaphainein to show through, from dia- + phainein to show — more at fancy  Date: 1614  1. characterized by such fineness of texture as to permit seeing through ~ fabrics  2. characterized by extreme delicacy of form ; ethereal painted ~ landscapes  3. insubstantial, vague had only a ~ hope of success  • ~ly adverb  • ~ness noun