Mai daidaitawa shine siffa mai girma uku mai fuska shida, kowanne daga cikinsu yana kamanceceniya. Hakanan ana kiranta da parallelepipedon ko parallelepipedon. Kalmar ta fito daga kalmomin Helenanci "parallelos" ma'ana a layi daya, da "epipedon" ma'ana saman. Ana yawan amfani da parallelepipeds a cikin lissafi da ingantattun makanikai don kwatantawa da tantance kaddarorin abubuwa masu girma uku. Misalai na gama-gari sun haɗa da prisms rectangular, cubes, da rhombic prisms.