Likely a nominalization of Middle English stencellen (“to garnish with bright hues”), borrowed from Middle French estinceller (“to glisten”), from Old French estenceler (“to spark”), from Old French estencele (“spark”), from Vulgar Latin *stincilla, from metathesis of Latin scintilla (“spark”).
The verb is from the noun.
stencil (plural stencils)
- A thin sheet, either perforated or using some other technique, with which a pattern may be produced upon a surface.
- A utensil that contains a perforated sheet through which ink can be forced to create a printed pattern on a surface.
- A two-ply master sheet for use with a mimeograph.
- “stencil” in Douglas Harper, Online Etymology Dictionary, 2001–2020.