Definify.com

Webster 1913 Edition

Adj.

[See

Capable of being wearied or tired out.

[R.]

Glanvill.

Adj.

Liable to be wearied.

defatigable ‎(comparative more defatigable, superlative most defatigable)

(very rare) Easily tired or wearied; capable of being fatigued.
- 2001: Cleveland Amory, The Cat Who Came for Christmas
  The author wishes to acknowledge the help of his peerful editor, Fredrica Friedman, and his defatigable researcher, Susan Hall, as well as that of his severest critic, P. Bear.