The Glycan Naming and Subsumption Ontology (GNOme) is an OBOFoundry ontology that organizes the stable glycan accessions of GlyTouCan glycan sequence registry for reasoning and browsing by subsumption. The ontology enables the fast, intuitive, and interactive exploration of GlyTouCan’s glycan structure accessions for glycan sequences; facilitates text-based lookup for common synonyms for structures and their GlyTouCan accessions; provides a framework for automated reasoning about glycan subsumption relationships; and annotates glycans with well-defined characterization categories. As part of the OBOFoundry, GNOme can be readily used by other ontology and standards initiatives to refer to glycans at varying degrees of characterization and is currently integrated with the GlyGen glycoinformatics resource to help users find “related glycans'' and to propagate species and glycan classification annotations by subsumption.