1) Boundless 2) Drainless 3) Exhaustless 4) Infinite 5) Productive 6) Unexhaustible 7) Unfailing 1) Infinite 2) Not exhaustible 3) Unlimited 4) Untiring 
• (a.) Incapable of being exhausted, emptied, or used up; unfailing; not to be wasted or spent; as, inexhaustible stores of provisions; an inexhaustible stock of elegant words.
In`ex·haust'i·ble adjective Incapable of being exhausted, emptied, or used up; unfailing; not to be wasted or spent; as, inexhaustible stores of provisions; an inexhaustible stock of elegant words. Dryden. « An inexhaustible store of anecdotes.» Macaulay....
[adj] - that cannot be entirely consumed or used up 2. [adj] - incapable of being entirely consumed or used up
unlimited adjective that cannot be entirely consumed or used up; `an inexhaustible supply of coal`
not exhaustible; incapable of being depleted: an inexhaustible supply. · untiring; tireless: an inexhaustible runner.