Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
interfātĭo, ōnis, f. [interfor], a speaking between, an interrupting in speaking (syn. interpellatio): contra verba atque interfationem, Cic. Sest. 37, 79: expositiones brevi interfatione distinguere, Quint. 4, 2, 50 Spald. N. cr.