योगवासिष्ठः yogavāsiṣṭhaḥ - book-5, chapter-66, verse-18

दुःखैः सुखलवाकारैर्दीर्घादीर्घैः शुभाशुभैः ।
अपर्याप्तागमापायाः प्रयान्त्यायान्ति रात्रयः ॥ १८ ॥

duḥkhaiḥ sukhalavākārairdīrghādīrghaiḥ śubhāśubhaiḥ ,
aparyāptāgamāpāyāḥ prayāntyāyānti rātrayaḥ 18

18. duḥkhaiḥ sukhalavākāraiḥ dīrghādīrghaiḥ śubhāśubhaiḥ
aparyāptāgamāpāyāḥ prayānti āyānti rātrayaḥ

18. aparyāptāgamāpāyāḥ rātrayaḥ duḥkhaiḥ sukhalavākāraiḥ
dīrghādīrghaiḥ śubhāśubhaiḥ prayānti āyānti

18. Nights, whose arrivals and departures are endless, come and go, characterized by sorrows that appear as mere fragments of happiness, by their fluctuating lengths, and by both good and bad aspects.

Words meanings summery:

• दुःखैः (duḥkhaiḥ) - by sorrows (by miseries, with sorrows)

• सुखलवाकारैः (sukhalavākāraiḥ) - that appear as mere fragments of happiness (whose form is a particle of happiness, appearing as fragments of happiness)

• दीर्घादीर्घैः (dīrghādīrghaiḥ) - by their fluctuating lengths (long and short, varying in length)

• शुभाशुभैः (śubhāśubhaiḥ) - by both good and bad aspects (good and bad, auspicious and inauspicious)

• अपर्याप्तागमापायाः (aparyāptāgamāpāyāḥ) - whose arrivals and departures are endless (whose comings and goings are endless/unsatisfied, whose arrivals and departures are insufficient)

• प्रयान्ति (prayānti) - they depart (they go forth, they depart)

• आयान्ति (āyānti) - they arrive (they come, they arrive)

• रात्रयः (rātrayaḥ) - nights

Words meanings and morphology

दुःखैः (duḥkhaiḥ) - by sorrows (by miseries, with sorrows)

(noun)

Instrumental, neuter, plural of duḥkha

duḥkha - sorrow, pain, misery, suffering

From dus (bad) + kha (space)

Note: Describes the nature of the nights.

सुखलवाकारैः (sukhalavākāraiḥ) - that appear as mere fragments of happiness (whose form is a particle of happiness, appearing as fragments of happiness)

(adjective)

Instrumental, masculine, plural of sukhalavākāra

sukhalavākāra - whose form is a particle of happiness, having the appearance of a speck of joy

Compound

Compound type : Bahuvrīhi (sukha+lava+ākāra)

• sukha – happiness, joy, comfort
  noun (neuter)
  From su (good) + kha (space)
• lava – particle, fragment, small portion
  noun (masculine)
  Root lū (to cut) + a suffix
  Root: lū (class 9)
• ākāra – form, shape, appearance, semblance
  noun (masculine)
  ā (prefix) + kāra (maker, form)
  Prefix: ā
  Root: kṛ (class 8)

Note: Qualifies 'duḥkhaiḥ'.

दीर्घादीर्घैः (dīrghādīrghaiḥ) - by their fluctuating lengths (long and short, varying in length)

(adjective)

Instrumental, neuter, plural of dīrghādīrgha

dīrghādīrgha - long and short, long and not long

Compound

Compound type : Dvandva (dīrgha+adīrgha)

• dīrgha – long, extended
  adjective
• adīrgha – not long, short
  adjective
  a (negation) + dīrgha

Note: Qualifies 'duḥkhaiḥ'.

शुभाशुभैः (śubhāśubhaiḥ) - by both good and bad aspects (good and bad, auspicious and inauspicious)

(adjective)

Instrumental, neuter, plural of śubhāśubha

śubhāśubha - good and bad, auspicious and inauspicious

Compound

Compound type : Dvandva (śubha+aśubha)

• śubha – good, auspicious, beautiful
  adjective
  Root: śubh (class 1)
• aśubha – not good, inauspicious, bad
  adjective
  a (negation) + śubha

Note: Qualifies 'duḥkhaiḥ'.

अपर्याप्तागमापायाः (aparyāptāgamāpāyāḥ) - whose arrivals and departures are endless (whose comings and goings are endless/unsatisfied, whose arrivals and departures are insufficient)

(adjective)

Nominative, feminine, plural of aparyāptāgamāpāya

aparyāptāgamāpāya - whose comings and goings are endless/unsatisfied, whose arrivals and departures are insufficient

Compound

Compound type : Bahuvrīhi (aparyāpta+āgama+apāya)

• aparyāpta – insufficient, endless, unfulfilled, not completed
  adjective
  Past Passive Participle (negative)
  a (negation) + pari (prefix) + root āp (to obtain) + kta suffix
  Prefixes: a+pari
  Root: āp (class 5)
• āgama – arrival, coming, approach
  noun (masculine)
  ā (prefix) + root gam (to go) + a suffix
  Prefix: ā
  Root: gam (class 1)
• apāya – departure, going away, loss, destruction
  noun (masculine)
  apa (prefix) + root i (to go) + a suffix
  Prefix: apa
  Root: i (class 2)

Note: Qualifies 'rātrayaḥ'.

प्रयान्ति (prayānti) - they depart (they go forth, they depart)

(verb)

3rd person , plural, active, present (laṭ) of prayā

Root yā (to go) + prefix pra, present tense

Prefix: pra

Root: yā (class 2)

Note: Paired with 'āyānti'.

आयान्ति (āyānti) - they arrive (they come, they arrive)

(verb)

3rd person , plural, active, present (laṭ) of āyā

Root yā (to go) + prefix ā, present tense

Prefix: ā

Root: yā (class 2)

Note: Paired with 'prayānti'.

रात्रयः (rātrayaḥ) - nights

(noun)

Nominative, feminine, plural of rātri

rātri - night

Root: rā

Note: Subject of the verbs 'prayānti' and 'āyānti'.