6. foil a thin layer of metal placed under a gem in a closed setting to improve its color or brilliancy.
7. foil a person or thing that makes another seem better by contrast.
8. foil an arc or rounded space between cusps.
9. foil an airfoil or hydrofoil.
10. (v.t.)foil to cover or back with foil.
11. foil to set off by contrast.
12. (n.)foil a flexible four-sided rapier having a blunt point.
13. foil foils, the art or practice of fencing with this weapon, points being made by touching the trunk of the opponent's body with the tip of the weapon.
Etymology: (1585–95; orig. uncert.)
Definition of 'FOIL'
Princeton's WordNet
1. (noun)foil a piece of thin and flexible sheet metal "the photographic film was wrapped in foil"
2. (noun)foil, enhancer anything that serves by contrast to call attention to another thing's good qualities "pretty girls like plain friends as foils"
3. (noun)hydrofoil, foil a device consisting of a flat or curved piece (as a metal plate) so that its surface reacts to the water it is passing through "the fins of a fish act as hydrofoils"
5. (verb)foil a light slender flexible sword tipped by a button
6. (verb)foil enhance by contrast "In this picture, the figures are foiled against the background"
7. (verb)thwart, queer, spoil, scotch, foil, cross, frustrate, baffle, bilk hinder or prevent (the efforts, plans, or desires) of "What ultimately frustrated every challenger was Ruth's amazing September surge"; "foil your opponent"
8. (verb)foil cover or back with foil "foil mirrors"
1. (noun)foil thin sheets of metal for protecting food
Definition of 'FOIL'
Webster Dictionary
1. (noun)FOIL failure of success when on the point of attainment; defeat; frustration; miscarriage
2. (noun)FOIL a blunt weapon used in fencing, resembling a smallsword in the main, but usually lighter and having a button at the point
3. (noun)FOIL the track or trail of an animal
4. (noun)FOIL a leaf or very thin sheet of metal; as, brass foil; tin foil; gold foil
5. (noun)FOIL a thin leaf of sheet copper silvered and burnished, and afterwards coated with transparent colors mixed with isinglass; -- employed by jewelers to give color or brilliancy to pastes and inferior stones
6. (noun)FOIL anything that serves by contrast of color or quality to adorn or set off another thing to advantage
7. (noun)FOIL a thin coat of tin, with quicksilver, laid on the back of a looking-glass, to cause reflection
8. (noun)FOIL the space between the cusps in Gothic architecture; a rounded or leaflike ornament, in windows, niches, etc. A group of foils is called trefoil, quatrefoil, quinquefoil, etc., according to the number of arcs of which it is composed
Definitions of FOIL 
Afrikaans: verydel; fnuik
Arabic: يُحْبِط، يُعَطِّل
Bulgarian: побеждавам
Brazilian: frustrar
Czech: zmařit
German: vereiteln
Danish: slå; skuffe
Greek: εμποδίζω, ματαιώνω, απογο
Spanish: frustrar
Estonian: nurjama
Farsi: شکست دادن؛ نقش بر آب کردن
Finnish: tehdä tyhjäksi
French: faireéchouer
Hebrew: לְסַכֵּל
Hindi: रोड़े अटकाना
Croatian: poraziti, spriječiti
Hungarian: meghiúsít
Indonesian: mengalahkan, menggagalkan
Icelandic: snúa á, hindra
Italian: frustrare
Japanese: 裏をかく
Korean: 실패하다
Lithuanian: (su)žlugdyti
Latvian: izjaukt (plānus u.tml.)
Malay: mengalahkan
Dutch: verijdelen
Norwegian: slå ut, forpurre, narre, 
Polish: pokonać
Persian: شکست دادن؛ نقش بر آب کردن
Pashto: ماته ورکول، مایوسه کول
Portuguese: frustrar
Romanian: aîmpiedica
Russian: срывать планы
Slovak: zmariť
Slovenian: poraziti
Serbian: poraziti
Swedish: besegra, kullkasta
Thai: ขัดขวาง
Turkish: engellemek, alıkoymak
Taiwanese: 挫敗
Ukrainian: розладнувати, порушувати 
Urdu: ناکام کرنا
Vietnamese: làm thất bại (một âm mưu,
Chinese: 挫败
