noun-modifying (irregular)
Prenominal adjective (attributive) meaning 'true' or 'real' in a fundamental sense. Often used in formal or emphatic contexts, such as 真の友情 (true friendship) or 真の原因 (the real cause).
He is a true friend.
The real cause is still unknown.
It takes time to understand the true meaning of this word.
Nobody knew his true purpose.
She showed her true self when she wasn't wearing makeup.
The real cause of the accident is still under investigation.
本物の describes something as genuine or authentic in a concrete, physical sense (a real diamond), while 真の is used more abstractly for qualities like friendship or purpose.
正真正銘の is an emphatic idiom meaning 'genuine, no mistake about it,' stronger and more colloquial than the plain formal 真の.
偽の means 'fake/false,' the direct opposite of 真の meaning 'true/real.'
Compound of 真 (しん, 'true') and the possessive/attributive particle の. The reading しん is the on'yomi of 真.