inexhaustible
Concise Oxford English Dictionary © 2008 Oxford University Press:
inexhaustible/ɪnɪɡˈzɔːstəbl/
▶adjective
- 1 (of a supply) never ending; incapable of being used up.
- 2 tireless.
– derivatives
inexhaustibility noun,
inexhaustibly adverb.
inexhaustibility noun,
inexhaustibly adverb.
'inexhaustible' also found in these Oxford entries:

