Correct spelling for the English word "inaptest" is [ɪnˈaptəst], [ɪnˈaptəst], [ɪ_n_ˈa_p_t_ə_s_t] (IPA phonetic alphabet).
The word "inaptest" is derived from the combination of the prefix "in-" which means "not" or "opposite of", and the noun "apt" which means "suitable" or "appropriate". The suffix "-est" denotes the superlative form of an adjective, indicating that "inaptest" is the most unsuitable or least appropriate.