I opened the new issue of New England Home magazine today and found a plug for some outdoor dining items:
"These ocean-smoothed-stone napkin rings are the perfect foil to that sudden gust of wind that can uproot an outdoor party. $42/SET OF FOUR"
Bravely hyphenated, unknown copy editor! But what does the word foil mean in this sentence? In fashion- and decor-speak, a foil is a complement. It's "one that by contrast underscores or enhances the distinctive characteristics of another," in AHD4's definition, via Wordnik. That foil, descended from Latin folium, leaf, has several senses related to contrast and reflection, including "a thin leaf of some metal placed under a precious stone to increase its brilliancy" (OED).
But "the perfect foil to that sudden gust of wind" suggests a different foil, the verb meaning "To prevent from being successful; thwart." This foil has a complicated history, but it is not related to the leafy foil; its noun form means "a defeat."
The shelter mag's "perfect foil" looks like a combination of the two senses -- it has the phrasing of the fashion cliche, but the meaning of the (obsolete?) noun foil. Is it a hidden eggcorn, like "stagger off this mortal coil" and similar variants that interpret "mortal coil" as the surface we tread? Or did an editor shorten an earlier version -- "these napkin rings are perfect for foiling that sudden gust of wind" -- to a more familiar phrase? (I've been an editor. It happens.)
I've never before seen "a perfect foil" meaning "a perfect foiler," but that doesn't mean it's not out there. Anyone have another example?