INDEMONSTRABLE Meaning of INDEMONSTRABLE in English [ ˌɪndɪ'mɒnstrəb(ə)l , ɪn'dɛmən- ]■ adjective not able to be proved or demonstrated. ↘ Philosophy (of a truth) axiomatic and hence not provable. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004