योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-170, verse-5

दुर्गदुर्गमदुर्वारदोषोद्धरणतत्परम् ।
सर्वविश्वासरत्नानां कोश आशैशवोषितम् ॥ ५ ॥

durgadurgamadurvāradoṣoddharaṇatatparam ,
sarvaviśvāsaratnānāṃ kośa āśaiśavoṣitam 5

5. durga-durgama-durvāra-doṣoddharaṇa-tatparam
sarvaviśvāsaratnānām kośaḥ āśaiśavoṣitam

5. (ekam akṛtrimam mitram) durga-durgama-durvāra-doṣoddharaṇa-tatparam (asti),
(ca) sarvaviśvāsaratnānām kośaḥ (asti),
āśaiśavoṣitam (ca asti).

5. It is devoted to eradicating faults that are difficult, inaccessible, and hard to overcome; it is a treasury of all jewels of trust, having resided [within one] since childhood.

Words meanings summery:

• दुर्ग-दुर्गम-दुर्वार-दोषोद्धरण-तत्परम् (durga-durgama-durvāra-doṣoddharaṇa-tatparam) - devoted to eradicating deep-seated and persistent faults (intent on removing faults that are difficult, inaccessible, and hard to overcome)

• सर्वविश्वासरत्नानाम् (sarvaviśvāsaratnānām) - of all the valuable aspects of trust and faith (of all jewels of trust/faith)

• कोशः (kośaḥ) - a treasury, a repository (treasury, storehouse, sheath, casket)

• आशैशवोषितम् (āśaiśavoṣitam) - that which has been present or resided within since childhood (dwelt in since childhood, present from infancy)

Words meanings and morphology

दुर्ग-दुर्गम-दुर्वार-दोषोद्धरण-तत्परम् (durga-durgama-durvāra-doṣoddharaṇa-tatparam) - devoted to eradicating deep-seated and persistent faults (intent on removing faults that are difficult, inaccessible, and hard to overcome)

(adjective)

neuter, singular of durga-durgama-durvāra-doṣoddharaṇa-tatpara

durga-durgama-durvāra-doṣoddharaṇa-tatpara - devoted to the removal of faults that are difficult (to approach), hard to traverse, and impossible to ward off.

A very long Tatpuruṣa compound ending in 'tatpara'. The first part 'durga-durgama-durvāra-doṣa' describes the type of faults.

Compound type : tatpuruṣa (durga+durgama+durvāra+doṣa+uddharaṇa+tatpara)

• durga – difficult to pass, inaccessible, hard to overcome (like a fortress)
  adjective
  From dus-√gam (to go badly, with difficulty).
  Prefix: dus
  Root: gam (class 1)
• durgama – difficult to approach, inaccessible, hard to traverse
  adjective
  From dus-√gam (to go badly, with difficulty).
  Prefix: dus
  Root: gam (class 1)
• durvāra – difficult to prevent, irresistible, hard to ward off
  adjective
  From dus-√vṛ (to ward off, stop).
  Prefix: dus
  Root: vṛ (class 5)
• doṣa – fault, defect, vice, error, impurity
  noun (masculine)
  From root √duṣ (to be corrupt, faulty).
  Root: duṣ (class 4)
• uddharaṇa – lifting up, extraction, removal, deliverance
  noun (neuter)
  From ud-√dhṛ (to lift up, extract) + ana suffix.
  Prefix: ud
  Root: dhṛ (class 1)
• tatpara – intent on, devoted to, absorbed in
  adjective
  Compound of 'tat' (that) + 'para' (foremost, intent on).

Note: Adjective describing 'mitram'.

सर्वविश्वासरत्नानाम् (sarvaviśvāsaratnānām) - of all the valuable aspects of trust and faith (of all jewels of trust/faith)

(noun)

Genitive, neuter, plural of sarvaviśvāsaratna

sarvaviśvāsaratna - a jewel of all trust/faith

Compound: 'sarva' (all) + 'viśvāsa' (trust) + 'ratna' (jewel).

Compound type : tatpuruṣa (sarva+viśvāsa+ratna)

• sarva – all, every, whole
  adjective
• viśvāsa – trust, faith, confidence
  noun (masculine)
  From vi-√śvas (to trust).
  Prefix: vi
  Root: śvas (class 2)
• ratna – jewel, gem, treasure
  noun (neuter)

Note: Modifies 'kośaḥ'.

कोशः (kośaḥ) - a treasury, a repository (treasury, storehouse, sheath, casket)

(noun)

Nominative, masculine, singular of kośa

kośa - treasury, store-room, casket, sheath, budget

From root √kuś (to collect, enclose).

Root: kuś (class 9)

आशैशवोषितम् (āśaiśavoṣitam) - that which has been present or resided within since childhood (dwelt in since childhood, present from infancy)

(adjective)

neuter, singular of āśaiśavoṣita

āśaiśavoṣita - dwelt in from childhood, present since infancy

Compound of 'āśaiśava' (from childhood) and 'uṣita' (dwelt, resided). It's a tatpuruṣa compound. 'uṣita' is the PPP of '√vas' (to dwell).

Compound type : tatpuruṣa (āśaiśava+uṣita)

• āśaiśava – from childhood, since infancy
  indeclinable/adjective (neuter)
  From 'ā' (up to, until) + 'śaiśava' (childhood).
  Prefix: ā
• uṣita – dwelt, resided, stayed
  adjective
  Past Passive Participle
  PPP of root '√vas' (to dwell).
  Root: vas (class 1)