Not able to be replaced; unique in value or characteristics.

Referring to something that holds a special status and cannot be substituted.

अप्रतिम

English Usage: "Her contributions to the team were irreplaceable."

Hindi Usage: "उसके योगदान टीम के लिए अप्रतिम थे।"

Essential and cannot be done without; indispensable.

आवश्यक

English Usage: "His role in the project was deemed irreplaceable."

Hindi Usage: "उसकी भूमिका परियोजना में आवश्यक मानी जाती थी।"