סִידּוּק, (סָרַק) being cracked; (sub. עיסת) dough, the surface of which is cracked in consequence of fermentation. Pes. III, 5 ס׳ ישרף dough in the stage of sidduḳ (during Passover) must be burnt; expl. נתערבו סדקיו, v. סֶדֶק; ib. 48ᵇ; Mekh. Bo s. 9; a. e.