— indefatigability, indefatigableness , n. — indefatigably , adv.
/in'di fat"i geuh beuhl/ , adj.
incapable of being tired out; not yielding to fatigue; untiring.
[ 1580-90; indefatigabilis untiring, equiv. to in- IN- 3 + defatiga ( re ) to tire out (see DE-, FATIGUE) + -bilis -BLE ]
Syn . tireless, inexhaustible, persevering.