plural of indefinite pronoun

The state of being indefatigable.

In an indefinable manner

That which cannot be precisely defined or put into words. / That which defies description; indescribable.

Anything that cannot be defined.

In an indefensible manner.

In an indefeasible manner.

Not liable to being annulled or declared void.

Tirelessness; persistence; stamina.

plural of indefatigability