Definition of defeasible in US English:



Law Philosophy
  • Open in principle to revision, valid objection, forfeiture, or annulment.

    • ‘In the jargon, this means that any scientific claim is defeasible, meaning it is in principle open to revision or rejection in the light of further disclosures, arguments, or evidence.’
    • ‘What they hold to be true is certain, not defeasible.’
    • ‘Each of these would-be reasons is defeasible and has been more than adequately seen off in argument during recent weeks.’
    • ‘They were not in any way, shape or form defeasible.’
    • ‘A second element of positive analogy between these two presumptions is that both are defeasible; and that they are, consequently, not to be identified with assumptions.’


Middle English: via Anglo-Norman French from the stem of Old French desfesant ‘undoing’ (see also defeasance).