o·ver·lap • v. / ˌōvərˈlap/ (-lapped, -lap·ping) [tr.] extend over so as to cover partly: the canopy overlaps the house roof at one end| [intr.] the curtains overlap at the center when closed. ∎  [intr.] cover part of the same area of interest, responsibility, etc.: their duties sometimes overlapped. ∎  [intr.] partly coincide in time: two new series overlapped.• n. / ˈōvərˌlap/ a part or amount that overlaps: an overlap of about half an inch. ∎  a common area of interest, responsibility, etc.: there are many overlaps between the approaches | there is some overlap in requirements. ∎  a period of time in which two events or activities happen together.

overlap An unconformable relationship in which a transgressive sequence (see TRANSGRESSION) of progressively younger members of an upper series of strata onlap and rest upon the underlying (oldest) stratum. Strictly, ‘onlap’ refers to the process and ‘overlap’ to the resulting structural relationship, but the two terms are often used synonymously. The opposite of overlap is ‘offlap’. See also OVERSTEP.

overlap A form of parallelism in which events that are not mutually dependent take place concurrently in order to increase computer performance, e.g. fetching a second instruction while a first instruction is being executed. When there is overlap between portions of arithmetic operations (i.e. when the portions are overlapped), the process is usually called pipelining.