Antonyms for the word "not registered" are registered, enrolled, recorded, listed, documented, endorsed, certified, validated, authorized, and approved. Being registered is crucial for availing several benefits and opportunities, like voting, education, healthcare, and financial assistance. Without registration, one can miss out on many opportunities and services that require identification and verification. Getting enrolled in various programs and activities is also equally important for personal and professional growth. Being documented and certified can add credibility and authenticity to one's credentials, which helps in building trust and confidence among peers and employers. Therefore, it is highly recommended to get registered, recorded, and validated for a fulfilling and successful life.