Correct spelling for the English word "placuntoma" is [plˌakəntˈə͡ʊmə], [plˌakəntˈəʊmə], [p_l_ˌa_k_ə_n_t_ˈəʊ_m_ə] (IPA phonetic alphabet).
A tumor originating in a portion of a retained placenta.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.