Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
The word interiectivus could not be parsed. Trying a normal dictionary lookup:
interjectīvus, a, um, adj. [interjacio], placed between (post-class.): rigor, Simplic. de Re Agrar. p. 78.
Hence, in-terjectīvē, adv., in the manner of an interjection, Prisc. 15 fin.