Where does “invalid” come from?

Invalid comes from Latin invalidus, formed from the prefix in- meaning "not" and the root oyd- via Proto-Indo-European ne meaning "not," ultimately tracing to the sense of lacking strength or force.

invalid (English): Not valid; not true, correct, acceptable or...

Definitions

  1. Not valid; not true, correct, acceptable or...

Ancestry of “invalid”, step by step

invalid traces back through two separate lines of ancestry.

via English valid

StepLanguageWordMeaning
1EnglishvalidWell grounded or justifiable, pertinent;...
2Middle Frenchvalidehealthy, sound, in good order
3Latinvalidusstrong; healthy, well; worthy
4Latinvaleōto have strength, influence, power; to avail
5Proto-Italicwalēōto be strong
6Proto-Indo-Europeanh₂wl̥h₁éh₁yeti
7Proto-Indo-Europeanh₂welh₁-to rule; strong, powerful; hair; wool

via Middle French invalide

StepLanguageWordMeaning
1Middle Frenchinvalide
2Latininvalidusinfirm, impotent, weak, feeble

Words derived from “invalid

Every word from Proto-Indo-European h₂welh₁-