interminable /ɪnˈtɜː(ɹ).mɪn.ə.bəl/adjective 1noun 1forms 3 adjective1 •Existing or occurring without interruption or end; ceaseless, unending.The sea-reach of the Thames stretched before us like the beginning of an interminable waterway. — 1899 noun1 •(old-fashioned) A repeating decimal. formsinterminables · more interminable · most interminable