Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
laeta, ōrum, v. 2. laetus.
2. laetus, i, m., in late Lat., a foreign bondman who received a piece of land to cultivate, for which he paid tribute to his master, a serf, Amm. 20, 8, 13; Eum. Pan. 21, 1.
Hence,