When the gopīs began to talk among themselves, they said, ‘Dear friends, the gopī who has been taken away by Kṛṣṇa to a secluded place must have worshiped the Lord more than anyone else.’
The name Rādhā is derived from this verse (Bhāg. 10.30.28), from the words anayārādhitaḥ, meaning “by Her the Lord is worshiped.” Sometimes the critics of Śrīmad-Bhāgavatam find it difficult to find Rādhārāṇī‘s holy name, but the secret is disclosed here in the word ārādhitaḥ, from which the name Rādhā has come. Of course, the name of Rādhārāṇī is directly mentioned in other Purāṇas. This gopī‘s worship of Kṛṣṇa is topmost, and therefore Her name is Rādhā, or the topmost worshiper.
Ref>>Srila Prabhupada Vani.