Correct spelling for the English word "cotoin" is [kˈɒtɔ͡ɪn], [kˈɒtɔɪn], [k_ˈɒ_t_ɔɪ_n] (IPA phonetic alphabet).
A bitter principle, C14H12O4, obtained from coto bark, occurring in the form of a yellow crystalline powder; dose gr. 1/2-2 (0.03-0.13).
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.