in ‧ ex ‧ haus ‧ ti ‧ ble /ˌɪnɪɡˈzɔːstəb ə l◂, ˌɪnɪɡˈzɔːstɪb ə l◂ $ -ˈzɒːs-/ BrE AmE adjective
something that is inexhaustible exists in such large amounts that it can never be finished or used up:
She has an inexhaustible supply of funny stories.
a man of inexhaustible energy