出典:Wiktionary
Back-formation from defeasance + -ible, from Anglo-Norman defesaunce, Old French desfaisance, a deverbal noun from desfaire (“to undo”) (Modern French défaire), from des- (“un-, apart”) + fere, faire (“to do”) + -able, reflecting Latin dis- + facere + -ābilis. Near-doublet of defeatable.
defeasible (comparative more defeasible, superlative most defeasible)