noun which may take the genitive case particle 'no', noun
Medical term meaning a condition arises spontaneously or from an unknown cause, not secondary to another disease. Used in compounds like 原発性高血圧 (primary hypertension).
原発性アルドステロン症は二次性高血圧の原因の一つです。
Primary aldosteronism is one cause of secondary hypertension.
Also means 'idiopathic' or 'of unknown cause', often used interchangeably with 原発性 in some contexts, but 原発性 emphasizes 'primary' as opposed to 'secondary'.
Compound of 原発 (げんぱつ, 'primary occurrence') + 性 (せい, '-ity, nature'), forming a medical term meaning 'primary' in the sense of originating spontaneously.