The Biomarker Ontology (BMO) is a comprehensive knowledge representation involving a variety of fields of medical and biological aspects. BMO is built in line with Basic Formal Ontology (BFO) and Open Biological and Biomedical Ontology (OBO) principles.Entities and definitions are added by reviewing the biomarker ontology (created by Fraunhofer SCAI 10 years ago and used for the validation of the companion biomarker for a anticancer drug), as well as collected from scientific publications and books from different fields capturing various diseases. The ontology is proposed to be used for improving biomarker identification tasks, as well as a supportive integratable tool for abundant AI techniques, such as Machine Learning (ML) and Large Learning Model (LLM).Biomarker Ontology (BMO), created by Fraunhofer SCAI, islicensed under CC BY 4.0. You are free to share (copy and redistributethe material in any medium or format) and adapt (remix, transform, andbuild upon the material) for any purpose, even commercially. for anypurpose, even commercially. The licensor cannot revoke these freedoms aslong as you follow the license terms. You must give appropriate credit(by using the original ontology IRI for the whole ontology and originalterm IRIs for individual terms), provide a link to the license, andindicate if any changes were made. You may do so in any reasonablemanner, but not in any way that suggests the licensor endorses you oryour use.