Word Study
Insessores
CIDE DICTIONARY
Insessores, n. pl. [NL., fr. L. insessor, lit., one who sits down, fr. incidere. See Insession.].
An order of birds, formerly established to include the perching birds, but now generally regarded as an artificial group. [1913 Webster]
For further exploring for "Insessores" in Webster Dictionary Online