Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Plătaeae, ārum, f., = Πλαταῖαι, Platœa, a city in Bœotia, celebrated for a victory of the Greeks over the Persians, now Kokla, Cic. Off. 1, 18, 61; Nep. Arist. 2, 1; id. Paus. 1, 2; Just. 2, 12, 11 al.
Hence,