That cannot be entirely consumed or used up: an inexhaustible supply of coal. (adjective)
Never wearying; tireless: an inexhaustible campaigner. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "inexhaustible" in a sentence
"_boundless_ steppes of the south an inexhaustible pasturage to present (54) _inexhaustible_ those nomad tribes whose numerous fields of pasturage, and give and incomparable horsemen form the birth to those nomad tribes, in chief defence of the empire. whose numerous and incomparable horsemen the chief defence of the empire,  as of all Oriental states, (15 _a_) _is to be found_."
"But there is no doubt that the term inexhaustible can with justice be applied to its stores."
"By doing so, you made it possible for nitrogen to be made available to mankind in inexhaustible quantities, in a form suitable for agriculture, and even at lower prices than hitherto."