Ācārya
आचार्यācāryaĀcārya is the teacher in the full sense: one who has learned the sacred texts, lives by what they teach, and teaches it to others. The word is traditionally explained as one who gathers the meaning of the texts and establishes the pupil in right conduct, and who does so by living it himself. The title is also an honour borne in names such as Yāmunācārya.
In the Śrīvaiṣṇava tradition the ācārya is the pupil's guide to the Lord. The ācārya gives the initiation and the sacred mantras, and recommends the pupil to the Lord, as Śrī does. The tradition remembers its line of ācāryas, beginning with the Lord Himself and Śrī, through Nāthamuni and Āḷavandār to Rāmānuja and the teachers who followed, and the pupil is taught to hold the ācārya in the highest honour.
The hymn itself calls the Lord the teacher in the name Kapilācārya (538), recalling the sage Kapila, born to Dēvahūti, who taught her the way to freedom. On the People page the ācāryas run from Nāthamuni to Parāśara Bhaṭṭar, who himself had Embār for his ācārya.
SourcesSimple guide to Srivaishnavam: acharya sishya relationship (granthams.koyil.org)Nathamuni (Wikipedia)Sri Vaishnavism (Wikipedia)