Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Paeŏnes, um, m., = Παίονες, a people of Macedonia, in that part of it afterwards called Emathia, the Pœonians, Ov. P. 2, 2, 77; id. M. 5, 313.
Sing.: Paeŏn, ŏnis, m., = Παίων, a Pœonian, Liv. 42, 51, 6.
Hence,
Paeŏnis, ĭdis, v. Paeones, B.