Origin: Germanic Old English prefix
Overlap has 7 different meanings across 2 categories:
a representation of common ground between theories or phenomena
"there was no overlap between their proposals"
the property of partial coincidence in time
"The two meetings were scheduled to overlap, so we had to find another time slot."
Something that overlaps or is overlapped
"The schedule shows where my classes overlap during lunch break."
In plain English: Overlap is when two things share some of the same space, time, or area so they are not completely separate from each other.
"There is always some overlap between their schedules, so they meet for coffee on Tuesdays and Thursdays."
To extend over and partly cover something.
"The roof tiles are arranged so that each one overlaps the row beneath it to keep water from leaking through."
In plain English: To overlap means for two things to cover part of each other while still being separate at some points.
"The two meetings overlap, so I cannot attend both at once."
Usage: Use overlap as an intransitive verb to describe when two objects share the same space without one necessarily acting upon the other. Avoid using it transitively unless you are specifically describing a forceful action of covering, which often requires a different phrasing like "cover over."
The word comes from combining the prefix over- with lap, meaning to fold or cover part of something. It entered English as a direct formation describing one thing covering another.