योगवासिष्ठः yogavāsiṣṭhaḥ - book-5, chapter-83, verse-17

अशङ्कितनभःकोशपतिताकुलपूरवत् ।
नापतन्ति विकल्पौघाश्चिरं वैकल्यकारिणः ॥ १७ ॥

aśaṅkitanabhaḥkośapatitākulapūravat ,
nāpatanti vikalpaughāściraṃ vaikalyakāriṇaḥ 17

17. aśaṅkitanabhaḥkośapatitākulapūravat na
āpatanti vikalpaughāḥ ciram vaikalyakāriṇaḥ

17. ciraṃ vaikalyakāriṇaḥ vikalpaughāḥ,
aśaṅkitanabhaḥkośapatitākulapūravat,
na āpatanti.

17. Conceptualizations (vikalpa) and doubts, which cause distress for a long time, do not descend like a turbulent flood rushing down from an unexpected celestial reservoir.

Words meanings summery:

• अशङ्कितनभःकोशपतिताकुलपूरवत् (aśaṅkitanabhaḥkośapatitākulapūravat) - like a turbulent flood fallen from an unexpected sky-reservoir

• न (na) - not, no

• आपतन्ति (āpatanti) - they fall down, they descend, they arrive

• विकल्पौघाः (vikalpaughāḥ) - floods of conceptualizations/doubts, multitudes of conceptualizations/doubts

• चिरम् (ciram) - for a long time, long

• वैकल्यकारिणः (vaikalyakāriṇaḥ) - causing agitation/distress

Words meanings and morphology

अशङ्कितनभःकोशपतिताकुलपूरवत् (aśaṅkitanabhaḥkośapatitākulapūravat) - like a turbulent flood fallen from an unexpected sky-reservoir

(indeclinable)

Complex compound with '-vat' suffix indicating similarity.

Note: The entire expression acts as an adverb modifying the manner of falling.

न (na) - not, no

(indeclinable)

आपतन्ति (āpatanti) - they fall down, they descend, they arrive

(verb)

3rd person , plural, active, present indicative (lat) of āpat

Prefix: ā

Root: pat (class 1)

विकल्पौघाः (vikalpaughāḥ) - floods of conceptualizations/doubts, multitudes of conceptualizations/doubts

(noun)

Nominative, masculine, plural of vikalpaugha

vikalpaugha - flood/multitude of conceptualizations/doubts

Compound type : ṣaṣṭhī-tatpuruṣa (vikalpa+ogha)

• vikalpa – conceptualization, doubt, alternative, mental construct
  noun (masculine)
• ogha – flood, stream, multitude, mass
  noun (masculine)

चिरम् (ciram) - for a long time, long

(indeclinable)

Note: Used here adverbially.

वैकल्यकारिणः (vaikalyakāriṇaḥ) - causing agitation/distress

(adjective)

Nominative, masculine, plural of vaikalyakārin

vaikalyakārin - causing agitation/defect/distress

Compound type : upapada-tatpuruṣa (vaikalya+kārin)

• vaikalya – defect, deficiency, agitation, distress
  noun (neuter)
• kārin – causing, making, doing
  adjective (masculine)
  agent noun / present active participle suffix
  Derived from root kṛ (to do, make) with suffix -in.
  Root: kṛ (class 8)