A type of ink that cannot be erased or removed.

A metaphorical use indicating something that cannot be forgotten or removed from memory.

ऐसा जो भूला नहीं जा सके

English Usage: The experience left an indelible mark on her life.

Hindi Usage: उस अनुभव ने उसके जीवन पर मिटाने योग्य निशान छोड़ दिया।