The Royal Anointing
Pattābhiṣekam (Sanskrit: patta = crown/turban + abhiṣeka = anointing; 'the anointing of the crown') refers to the royal coronation ceremony — the formal enthronement of a king, deity, or Ācārya with all royal honors. In the Rāmāyaṇa, Rāma's pattābhiṣekam at Ayodhyā is the joyous culmination of the entire narrative.
In Temple Worship
In Śrī Vaiṣṇava temple practice, pattābhiṣekam may refer to special coronation services performed for the utsavar deity on specific festival days — when the Lord is crowned with elaborate royal regalia (crown, jewels, weapons) and worshipped as the King of Kings. This service expresses Bhagavān's aiśvarya (sovereign glory).
Ācārya Pattābhiṣekam
The formal installation of a new jīyar or the successor to an Ācārya-pīṭham may also be called pattābhiṣekam, since the person is ceremonially entrusted with the seat, responsibilities, and insignia of the lineage. This usage should be distinguished from the celebrated Śrīraṅgam episode in which Maṇavāḷa Māmunigaḷ expounded the Īḍu commentary before Namperumāḷ and received the Śrīśailēśa-dayāpātram taniyan from the Lord in the form of a young disciple. That event manifests Raṅganātha's acceptance of Māmunigaḷ as Ācārya; it is not accurately described simply as Māmunigaḷ's formal pattābhiṣekam or installation at Śrīraṅgam.