Śloka — A Sanskrit Metrical Verse
A śloka is, in broad usage, a Sanskrit metrical verse. In the classical epics the word often refers specifically to the epic anuṣṭubh form: four pādas of eight syllables, conventionally printed as two half-verses, for a total of 32 syllables. The Rāmāyaṇa, Mahābhārata, Bhagavad Gītā, and many Purāṇic passages are predominantly composed in this form.
The traditional account connects the first human śloka with Vālmīki’s grief (śoka) on seeing one of the krauñca birds killed. This is a sacred literary etiology; the grammatical derivation of śloka should not be stated from invented roots such as śru meaning “to flow” or “to praise.”
In Śrī Vaiṣṇava usage, śloka is also commonly used in the broader sense for a Sanskrit verse even when its metre is not anuṣṭubh. Āchārya stotras employ many metres, and prose works such as the Gadyatrayam are not ślokas merely because they are sacred Sanskrit compositions. The term should therefore be broad enough for actual usage while retaining the technical anuṣṭubh sense where prosody is being discussed.
Students memorize ślokas from the Bhagavad Gītā, Viṣṇu Purāṇa, stotras, and Vedāntic works as part of svādhyāya and kālakṣepam. The metrical form should be identified text by text rather than assuming that every Sanskrit verse is anuṣṭubh.