WordNet sense 1 (so thin as to transmit light):

cobwebby, diaphanous, filmy, gauzy, gossamer, see-through, sheer, vaporous, gauze-like, vapourous

WordNet sense 2 (of relatively small extent from one surface to the opposite or in cross section):

thin

WordNet sense 3 (free of deceit):

guileless

WordNet sense 4 (characterized by honesty and fairness):

square, straight

WordNet sense 5 (easily perceived by the senses or grasped by the mind):

obvious

WordNet sense 6 (transmitting light; able to be seen through with clarity):

crystalline, limpid, lucid, pellucid, crystal clear

WordNet sense 7 (free from cloudiness; allowing light to pass through):

clear