Tristubh is the name of a Vedic meter of 44 syllables (four padas of eleven syllables each), or any hymn composed in this meter. It is the most prevalent meter of the Rigveda, accounting for roughly 40% of its verses.
The tristubh pada contains a "break" or caesura, after either four or five syllables, necessarily at a word-boundary and if possible at a syntactic break, followed by either three or two short syllables. The final four syllables form a trochaic cadence. For example RV 2.3.1:a b c d "Agni is set upon the earth well kindled / he standeth in the presence of all beings. / Wise, ancient, God, the Priest and Purifier / let Agni serve the Gods for he is worthy." (trans. Griffith; note that the translator attempts to imitate the meter in English)
Is to be read metrically asa υ----,υυ|-υ-x b ----υ,υυ|-υ-x c ---υ-,υυ|-υ-x d ----,υυυ|-υ-x
with , marking the caesura and | separating the cadence:a | b | c | d |
The Avesta has a parallel stanza of 4x11 syllables with a caesura after the fourth syllable.
Tristubh verses are also used in later literature, its archaic associations used to press home a "Vedic" character of the poetry. The Bhagavad Gita, while mostly composed in shloka (developed from the Vedic Anustubh) is interspersed with Tristubhs, for example in the passage beginning at chapter 11, verse 15, when Arjuna begins speaking in Tristubhs.