(of ink or a pen) making marks that cannot be removed.
I remember a story of Estee Lauder visiting one of her makeup counters and overhearing a customer asking a sales associate how long a lipstick would wear. The associate told the customer that it was practically indelible. Ms. Lauder interrupted, and corrected her. “If it were indelible, my dear, I would never sell more.”
I love this word. It is so clear in its meaning, yet very rarely used. Make it an indelible part of your vocab today!