Two ontologies have been developed to characterize traits in vertebrate species. The Vertebrate Trait Ontology (VT) is a vocabulary of terms describing measurable or observable characteristics related to the morphology, physiology, or development of vertebrates. The livestock Product Trait Ontology (PT) defines those characteristics relevant to products produced by or obtained from animals maintained for use and/or profit. Both ontologies are being used to annotate data in the Animal QTL Database, providing a common basis for comparisons across databases or between species. The VT and PT will benefit the livestock production industry by implementing standardized trait nomenclature to enhance animal improvement accuracy and to unambiguously utilize research outcomes.