Entry 1 sense Webster, 1913 Paleornithology /(pā`lē̇*ôr`nĭ*thŏl"ō̇*jy̆)/ · Pa·le·or·ni·thol·o·gy · IPA 01 n. The branch of paleontology which treats of fossil birds. 1. The branch of paleontology which treats of fossil birds.