योगवासिष्ठः yogavāsiṣṭhaḥ - book-5, chapter-84, verse-7

तथाभितिष्ठतस्तस्य संवत्सरशतत्रयम् ।
कोटरे विन्ध्यकच्छस्य ययावर्धमुहूर्तवत् ॥ ७ ॥

tathābhitiṣṭhatastasya saṃvatsaraśatatrayam ,
koṭare vindhyakacchasya yayāvardhamuhūrtavat 7

7. tathā abhitiṣṭhatas tasya saṃvatsaraśatatrayam
koṭare vindhyakacchasya yayau ardhamuhūrtavat

7. tasya vindhyakacchasya koṭare tathā abhitiṣṭhatas
saṃvatsaraśatatrayam ardhamuhūrtavat yayau

7. While he remained standing in a tree hollow within the Vindhya region, three hundred years passed for him as if they were merely half a *muhūrta*.

Words meanings summery:

• तथा (tathā) - thus (thus, so, in that manner)

• अभितिष्ठतस् (abhitiṣṭhatas) - while remaining standing (standing over, remaining, staying, being present)

• तस्य (tasya) - for him (his, of him, to him, for him)

• संवत्सरशतत्रयम् (saṁvatsaraśatatrayam) - three hundred years

• कोटरे (koṭare) - in the hollow (of a tree) (in the hollow, in the cavity, in the tree-trunk)

• विन्ध्यकच्छस्य (vindhyakacchasya) - of the Vindhya region (of the Vindhya region, of the Vindhya forest)

• ययौ (yayau) - passed (time) (went, passed, proceeded)

• अर्धमुहूर्तवत् (ardhamuhūrtavat) - like half a muhūrta (a traditional unit of time) (like half a muhūrta)

Words meanings and morphology

तथा (tathā) - thus (thus, so, in that manner)

(indeclinable)

अभितिष्ठतस् (abhitiṣṭhatas) - while remaining standing (standing over, remaining, staying, being present)

(participle)

Genitive, masculine, singular of abhitiṣṭhat

abhitiṣṭhat - standing, remaining, being present

Present Active Participle

Derived from root sthā (to stand) with prefix abhi, in present tense active voice.

Prefix: abhi

Root: sthā (class 1)

Note: The form abhitiṣṭhatas is genitive singular of abhitiṣṭhat, agreeing with tasya.

तस्य (tasya) - for him (his, of him, to him, for him)

(pronoun)

Genitive, masculine, singular of tad

tad - that, he, it

Note: Agrees with the implied subject of abhitiṣṭhatas.

संवत्सरशतत्रयम् (saṁvatsaraśatatrayam) - three hundred years

(noun)

Nominative, neuter, singular of saṃvatsaraśatatraya

saṁvatsaraśatatraya - three hundred years

Compound type : dvigu (saṃvatsara+śata+traya)

• saṃvatsara – year
  noun (masculine)
• śata – hundred
  noun (neuter)
• traya – three
  noun (neuter)

Note: Functions as the subject of yayau.

कोटरे (koṭare) - in the hollow (of a tree) (in the hollow, in the cavity, in the tree-trunk)

(noun)

Locative, neuter, singular of koṭara

koṭara - hollow, cavity (especially of a tree), hole

Note: Specifies location.

विन्ध्यकच्छस्य (vindhyakacchasya) - of the Vindhya region (of the Vindhya region, of the Vindhya forest)

(noun)

Genitive, masculine, singular of vindhyakaccha

vindhyakaccha - region or forest of the Vindhya mountains

Compound type : tatpuruṣa (vindhya+kaccha)

• vindhya – Vindhya mountains (a mountain range in central India)
  proper noun (masculine)
• kaccha – forest, marshy land, bank, shore
  noun (masculine)

Note: Qualifies koṭare.

ययौ (yayau) - passed (time) (went, passed, proceeded)

(verb)

3rd person , singular, active, perfect (lit) of gam

Perfect tense, 3rd person singular, active voice.

Formed from root gam (to go)

Root: gam (class 1)

Note: The verb for saṃvatsaraśatatrayam (the subject).

अर्धमुहूर्तवत् (ardhamuhūrtavat) - like half a muhūrta (a traditional unit of time) (like half a muhūrta)

(indeclinable)

vat suffix indicating "like" or "as if".

Compound type : tatpuruṣa (ardha+muhūrta)

• ardha – half
  adjective (masculine/neuter)
• muhūrta – a moment, a traditional unit of time (approx. 48 minutes)
  noun (masculine)

Note: The vat suffix here makes it an indeclinable adverb meaning "like/as ardhamuhūrta".