A suffix meaning 'disease' used at the end of words; in the form ～びょう it denotes a specific illness or disorder (e.g., 伝染病, 精神病).
伝染病の予防には手洗いや消毒が重要だ。
Hand washing and disinfection are important to prevent infectious diseases.
彼は長年、精神病の治療を受けている。
He has been receiving treatment for a mental illness for many years.