The name APL

APL is named after Ken Iverson's book A Programming Language, following a suggestion by Adin Falkoff. Despite being the source of the name "APL", Iverson's book describes not APL, but Iverson notation. The name "APL" is used only for computer implementations of Iverson's language, starting with APL\360.

APL is occasionally re-interpreted to stand for Array Programming Language or Array Processing Language, thereby making APL into a backronym.

Falkoff coined the name in 1966 during the implementation of APL\360 at IBM. Eugene McDonnell writes that, after considering other names such as "Mathlab" (MATLAB did not yet exist), inspiration struck: "Then one day Adin Falkoff walked into Ken's office and wrote "A Programming Language" on the board, and underneath it the acronym "APL"."

A week later, Eric Iverson asserted to McDonnell that the name was already well known.

The letters APL are shared by many other entities. Roger Hui remarks that he "started in 1966 on an APL machine that weighed 15,000 tons, when I travelled from Hong Kong to San Francisco on the S.S. President Wilson of the American President Lines." See also It’s APL… but not as we know it! on the Dyalog blog. Amazon has created a JSON Schema for its virtual assistant, Alexa, called the Alexa Presentation Language. This is often abbreviated APL, and can thus create some confusion with the APL programming language.