Same entry in the Synagoge (tau62) and Photius' Lexicon (tau114 Theodoridis)-- but the headword and gloss, accusative plurals, are both textually corrupt. The headword should be tegktou/s, as in Hesychius tau309, where the gloss -- according to H.Stephanus' standard conjecture -- is xristou/s "able to be rubbed on."
Aristotle (Meteorologica 385b13 ff.) discusses the difference between substances like wool and earth that are tegkto/n and those like metals that are thkto/n. Perhaps these two similar adjectives became confused in the lexicographical tradition. The accusative plural must be quoted from an unknown source.