Where does “mad lib” come from?

mad lib (English) comes from English MAD, from Middle English mad, from Old English ġemǣd, from Proto-Germanic maidijaną, from Proto-Germanic maidaz, from Proto-Indo-European mēy- — soft, tender, dear.

mad lib (English): A humorously nonsensical story created from a template with blanks for certain elements. One participant supplies words to fill the blanks (e.g. "nose" where a body part is required), and the other reads the resulting story

Definitions

  1. A humorously nonsensical story created from a template with blanks for certain elements. One participant supplies words to fill the blanks (e.g. "nose" where a body part is required), and the other reads the resulting story

Ancestry of “mad lib”, step by step

mad lib traces back through two separate lines of ancestry.

via English MAD

StepLanguageWordMeaning
1EnglishMADInitialism of mutually assured destruction;...
2Middle EnglishmadMad, insane, deranged; not of sound mind;...
3Old Englishġemǣd
4Proto-Germanicmaidijanąto exchange, change
5Proto-Germanicmaidazhurt, wounded; mad, foolish; angry, enraged
6Proto-Indo-Europeanmēy-soft, tender, dear

via English ad lib

StepLanguageWordMeaning
1Englishad libAt pleasure; At will; To whatever extent
2Englishad libitumAs much as desired, to one's fill, without...
3New Latinad libitumat one's pleasure, allowing freedom to improvise,...
Every word from Proto-Indo-European mēy-Every word from Proto-Germanic maidazEvery word from Proto-Germanic maidijaną