omasum omasitis • omber · · · Info · Definitions · Synonyms · Characters · · omasum · · Text Latin · · Script 6 · · Length Definitions · · · (noun) the third compartment of the stomach of a ruminant. Synonyms: psalterium, third stomach. · · Noun Definition 1 Synonyms · · · psalterium · · Synonym 1 third stomach · · Synonym 2 Characters · · a latin small letter a U+0061 m latin small letter m U+006D o latin small letter o U+006F s latin small letter s U+0073 u latin small letter u U+0075