τετράδερμα

ατος, τό
A. leather mattress, ground sheet (cf. CR 47.211), POxy. 1294.4 (ii/iii A.D.), Dura4 155 (iii A.D.), restored in PSI 6.678 (iii B.C.); τετράδερμον, = segestrum, Gloss.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project