(ˈ)tāt|bāsh adjective
Etymology: French, noun, pair of inverted stamps, from tête head + bêche, short for obsolete French bechevet double bedhead, from French bes- (from Latin bis- ) + chevet bedhead, chevet — more at chevet
: of or relating to a pair of stamps inverted in relation to one another either as the result of an error in printing or intentionally so printed
a set of bicolor tête-bêche triangular stamps — A.H.Murphey