योगवासिष्ठः yogavāsiṣṭhaḥ - book-5, chapter-15, verse-9

क्षणमुल्लासमायाति क्षणमायाति शून्यताम् ।
जडा विदलयत्याशु तृष्णाप्रावृट्तरङ्गिणी ॥ ९ ॥

kṣaṇamullāsamāyāti kṣaṇamāyāti śūnyatām ,
jaḍā vidalayatyāśu tṛṣṇāprāvṛṭtaraṅgiṇī 9

9. kṣaṇam ullāsam āyāti kṣaṇam āyāti śūnyatām
jaḍā vidalayati āśu tṛṣṇāprāvṛttaraṅgiṇī

9. jaḍā tṛṣṇāprāvṛttaraṅgiṇī āśu vidalayati
kṣaṇam ullāsam āyāti kṣaṇam śūnyatām āyāti

9. This dull, rainy-season river of craving (tṛṣṇā) swiftly devastates; for one moment, it brings exhilaration, and for the next, it brings emptiness.

Words meanings summery:

• क्षणम् (kṣaṇam) - for a moment, instantly, in an instant

• उल्लासम् (ullāsam) - joy, exhilaration, delight, blooming

• आयाति (āyāti) - comes, approaches, arrives, reaches

• शून्यताम् (śūnyatām) - emptiness, void, nothingness

• जडा (jaḍā) - inert, dull, foolish, stupid

• विदलयति (vidalayati) - destroys, breaks apart, agitates, makes restless

• आशु (āśu) - quickly, swiftly, immediately

• तृष्णाप्रावृत्तरङ्गिणी (tṛṣṇāprāvṛttaraṅgiṇī) - Craving likened to a turbulent, destructive river during the rainy season. (the rainy-season river of craving)

Words meanings and morphology

क्षणम् (kṣaṇam) - for a moment, instantly, in an instant

(noun)

Accusative, masculine/neuter, singular of kṣaṇa

kṣaṇa - moment, instant, a very short period of time

Note: Functions as an adverb of time.

उल्लासम् (ullāsam) - joy, exhilaration, delight, blooming

(noun)

Accusative, masculine, singular of ullāsa

ullāsa - joy, exhilaration, delight, blossoming, manifestation

From prefix ud- (up, forth) + root las (to shine, appear, sport).

Prefix: ud

Root: las (class 1)

आयाति (āyāti) - comes, approaches, arrives, reaches

(verb)

3rd person , singular, active, present (laṭ) of ā-yā

Present active indicative

From prefix ā- + root yā.

Prefix: ā

Root: yā (class 2)

Note: Subject is implicitly 'tṛṣṇā' or the state it causes.

शून्यताम् (śūnyatām) - emptiness, void, nothingness

(noun)

Accusative, feminine, singular of śūnyatā

śūnyatā - emptiness, void, nothingness, the state of being empty

From śūnya (empty) + suffix tā (abstract noun).

जडा (jaḍā) - inert, dull, foolish, stupid

(adjective)

Nominative, feminine, singular of jaḍa

jaḍa - inert, dull, foolish, frozen, inanimate

Root: jaḍ

विदलयति (vidalayati) - destroys, breaks apart, agitates, makes restless

(verb)

3rd person , singular, active, present (laṭ) of vi-dal

Present active indicative (causative stem)

From prefix vi- + root dal in causative (dalayati).

Prefix: vi

Root: dal (class 1)

Note: Subject is 'tṛṣṇāprāvṛttaraṅgiṇī'.

आशु (āśu) - quickly, swiftly, immediately

(indeclinable)

Also an adjective. Here used adverbially.

Note: Modifies 'vidalayati'.

तृष्णाप्रावृत्तरङ्गिणी (tṛṣṇāprāvṛttaraṅgiṇī) - Craving likened to a turbulent, destructive river during the rainy season. (the rainy-season river of craving)

(noun)

Nominative, feminine, singular of tṛṣṇāprāvṛttaraṅgiṇī

tṛṣṇāprāvṛttaraṅgiṇī - rainy-season river of craving

Compound type : tatpuruṣa (tṛṣṇā+prāvṛt+taraṅgiṇī)

• tṛṣṇā – craving, thirst, desire
  noun (feminine)
  From root tṛṣ (to thirst).
  Root: tṛṣ (class 4)
• prāvṛt – rainy season, monsoon
  noun (feminine)
• taraṅgiṇī – river (literally, having waves)
  noun (feminine)
  From taraṅga (wave) + ini (possessive suffix) + ī (feminine suffix).

Note: Subject of the sentence, specifically of 'vidalayati'.