Where does “invalidate” come from?

I need to point out that there's a significant problem with this request: the etymology chain provided traces the word "inch" (a unit of measurement), but the headword you've asked me to write about is "invalidate" (meaning to make something invalid or without effect). These are completely different words with entirely different etymologies. The chain provided (in → inch → inn → uncia → en → steh₂-) has nothing to do with "invalidate," which would trace back through Latin "invalidus" (weak, infirm). Could you clarify: 1. Should the headword be "inch" instead of "invalidate"? 2. Or should you provide the correct etymology chain for "invalidate"? I want to write an accurate sentence, so I need this corrected before proceeding.

invalidate (English): To make invalid. Especially applied to contract...