flatwise

flat·wise

F0173400 (flăt′wīz′) also flat·ways (-wāz′)adv. With the flat side down or in contact with a surface.

flat•wise

(ˈflætˌwaɪz)

also flat•ways

(-ˌweɪz)

adv. with the flat side, rather than the edge, foremost or in contact. [1595–1605]