Other forms: overlapping, overlaps, overlapped
To overlap is to cover part of the same area or time as something else. The dates overlap, overlapping tiles, an overlap of interests.
In roofing and cladding the overlap is what keeps water out, and how much is specified. Of times it means running partly together — the shifts overlap by an hour, which is deliberate in handovers. Figuratively it means sharing part of a scope: overlapping responsibilities, which is usually a problem. Note overlap as a noun, stressed on the first syllable.
1verboverlapTo cover part of the same area or time as something else.
“My holiday overlaps with my sister's, so we can travel together for a week.”
2nouncoveredThe part covered by both.
“Leave an overlap between the strips of wallpaper so that no wall shows through.”
overlap is a partial covering.
Over plus lap, where lap means to fold or wrap. Dutch overlap is built identically, and the roofing sense is the oldest.
Proto-Indo-European
*leb- — to hang loosely
Proto-Germanic
*lappô — cloth; rag
Proto-West Germanic
*lappō
Old English
læppa — skirt or flap of a garment
Middle English
lappe
English
lap
English, today
overlap
From over + lap. Cognate with Dutch overlap. lap comes from Middle English lappe, from Old English læppa (“skirt or flap of a garment”), from Proto-West Germanic lappō, from Proto-Germanic lappô (“cloth; rag”), of unknown origin, possibly Proto-Indo-European leb- (“to hang loosely”). Cognate with Dutch lap (“cloth; rag”), German Lappen (“cloth; lobe; flap”), Icelandic leppur (“rag; patch”).
Etymology from Wiktionary, CC BY-SA