Correct spelling for the English word "signatured" is [sˈɪɡnɪt͡ʃəd], [sˈɪɡnɪtʃəd], [s_ˈɪ_ɡ_n_ɪ_tʃ_ə_d] (IPA phonetic alphabet).
The word "signatured" is derived from the verb "sign" combined with the past participle ending "-ed". The verb "sign" comes from the Latin word "signare" which means "to mark" or "to seal". Over time, it evolved into the Middle English word "signen" and later "signen" in Old French. The past participle ending "-ed" is a suffix used to form the past tense or past participle of regular English verbs. In this case, "signatured" is formed by adding "-ed" to the verb "sign", indicating an action of signing has already occurred.