English
proofful
From proof + -ful.
Formed from proof + -ful
Proto-Indo-European *pro-bʰH-wó-s ‘being in front’
…
Latin probō ‘to approve; to test’
Late Latin proba ‘a proof’
Old French prove
Middle English proof
English proof
Today it means
adj Serving to prove something.
Language periods are conventional ranges, not dates for this word.
Etymograph / proofful