As found in revolved triangle/trikoṇa, half-moon/ardhachandra and lateral angle/parśvākoṇa poses.
That underdotted ṛ is r-as-a-vowel, close to an Irish pronunciation of father. (It no longer occurs in Hindi where instead in Sanskrit words containing it they pronounce it as -ri-. So for tree pose you may see and hear either vṛkṣa or vriksha. So also ‘parivritta.’ But in the Indic scripts they look completely different, e.g. vṛ is वृ and vri is व्रि.)
Sanskrit words are (usually) built up out of readily analysable components, in this case:
pari + vṛt + ta: turned right around
pari- around, completely—compare periscope (‘look around’),
perennial (‘throughout the years’)
vṛt turn—compare revert (‘turn back’)
-ta (completed action, like -ed)
English has a near exact equivalence of parivṛtta in ‘perverted,’ a Latin import literally meaning ‘completely turned.’
A related word parivartana ‘a turning around’ occurs in the pose jaṭhara-parivartana-āsana, gut rotation pose.