indefeasible

adjective

in·​de·​fea·​si·​ble ˌin-di-ˈfē-zə-bəl 

: not capable of being annulled or voided or undone

an indefeasible right

indefeasibility

ˌin-di-ˌfē-zə-ˈbi-lə-tē 

noun

indefeasibly

ˌin-di-ˈfē-zə-blē 

adverb

Did you know?

We acquired "indefeasible" in the mid-16th century by combining the English prefix in- ("not") with "defeasible," a word borrowed a century earlier from Anglo-French. "Defeasible" itself can be traced to an Old French verb meaning "to undo" or "to destroy." It's no surprise, then, that something indefeasible is essentially "un-undoable" or "indestructible." Another member of this family of words is feasible, meaning "capable of being done or carried out." Ultimately, all three - "indefeasible," "defeasible," and "feasible" - can be traced back to the Latin verb facere, meaning "to do."

Word History

First Known Use

1548, in the meaning defined above

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Kids Definition

indefeasible

adjective

in·​de·​fea·​si·​ble ˌin-di-ˈfē-zə-bəl 

: impossible to abolish

indefeasible rights

indefeasibly

-ˈfē-zə-blē 

adverb

Legal Definition

indefeasible

adjective

in·​de·​fea·​si·​ble ˌin-di-ˈfē-zə-bəl 

: not capable of being annulled or voided

an indefeasible right

indefeasibly adverb