Plain Vanilla

Vanilla has multiple meanings.Vanilla, a flavoringVanillin, the pure form of the flavoringVanilla (orchid), the genus from which vanillin is derivedVanilla extract, a baking ingredient containing vanilla flavorVanilla is also commonly used to mean "plain" or "conventional," derived from the use of vanilla extract as the most popular flavoring for ice cream.Vanilla option, in finance, a "simple" or well understood optionVanilla sex, a term referring to what a society regards as standard or conventional human sexual behavior Vanilla software, referring to software that is used "as delivered"
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A term that refers to a relatively simple derivative  financial instrument, usually a swap or other derivative that is issued with standard features.

slang term for a product with only the most basic features; see Bells and Whistles.