The name is a compound of two Sanskrit words: Tulasī, which is an Indian variety of the basil plant considered auspicious by Vaishnavas (devotees of god Vishnu and his avatars like Rama), and Dāsa, which means slave or servant and by extension, devotee. Tulsidas, which means a servant of the plant Tulsi.
Tulsi is more than a simple nature name: The holy basil plant is sacred in the Hindu religion, used to honor the god Vishnu and representative of his consort, the goddess Tulsi. The Tulsi plant is often planted in Hindu houses and is used for medicinal as well as ritualistic purposes.