To lap or fold over; extend so as to lie or rest upon: as, one slate on a roof overlaps another.To cause to lap or fold over: as, to overlap slates or shingles on a roof.n. The lapping of one thing over another; also, the thing or part which overlaps; specifically, in geology, a disposition of the strata such that newer or more recent members of a formation lap over or are deposited beyond the limits of the older beds.