योगवासिष्ठः yogavāsiṣṭhaḥ - book-3, chapter-17, verse-24

पूर्वाब्धितटमाहेन्द्रसिद्धोक्तगगनापगम् ।
उत्तराब्धितटायातदूतवर्णितगुह्यकम् ॥ २४ ॥

pūrvābdhitaṭamāhendrasiddhoktagaganāpagam ,
uttarābdhitaṭāyātadūtavarṇitaguhyakam 24

24. pūrvābdhitaṭamāhendrasiddhoktagaganāpagam
uttarābhditaṭāyātadūtavarṇitaguhyakam

24. pūrvābdhitaṭamāhendrasiddhoktagaganāpagam
uttarābhditaṭāyātadūtavarṇitaguhyakam

24. Where the celestial river was spoken of by the perfected beings from the Mahendra mountain on the eastern ocean shore, and where the Guhyakas were described by messengers arriving from the northern ocean shore.

Words meanings summery:

• पूर्वाब्धितटमाहेन्द्रसिद्धोक्तगगनापगम् (pūrvābdhitaṭamāhendrasiddhoktagaganāpagam) - Describing a place where knowledge of distant, sacred geographical features and celestial phenomena is widespread due to interactions with accomplished sages. (Where the celestial river was spoken of by the Mahendra siddhas on the eastern ocean shore.)

• उत्तराभ्दितटायातदूतवर्णितगुह्यकम् (uttarābhditaṭāyātadūtavarṇitaguhyakam) - Indicating the extent of knowledge and connections of the kingdom, reaching far northern regions and encompassing descriptions of semi-divine beings. (Where the Guhyakas were described by messengers arriving from the northern ocean shore.)

Words meanings and morphology

पूर्वाब्धितटमाहेन्द्रसिद्धोक्तगगनापगम् (pūrvābdhitaṭamāhendrasiddhoktagaganāpagam) - Describing a place where knowledge of distant, sacred geographical features and celestial phenomena is widespread due to interactions with accomplished sages. (Where the celestial river was spoken of by the Mahendra siddhas on the eastern ocean shore.)

(adjective)

Accusative, neuter, singular of pūrvābdhitaṭamāhendrasiddhoktagaganāpaga

pūrvābdhitaṭamāhendrasiddhoktagaganāpaga - Having the celestial river spoken of by the Mahendra siddhas on the eastern ocean shore.

Compound type : Bahuvrīhi (pūrva+abdhi+taṭa+mahendra+siddha+ukta+gaganāpagā)

• pūrva – Eastern, former, prior.
  adjective (neuter)
• abdhi – Ocean, sea.
  noun (masculine)
• taṭa – Shore, bank, edge.
  noun (masculine)
• mahendra – Name of a mountain range; Great Indra.
  proper noun (masculine)
• siddha – Accomplished, perfected being, sage, adept.
  noun (masculine)
• ukta – Spoken, said, mentioned, declared.
  adjective (masculine)
  Past Passive Participle
  Derived from verb root `vac` (to speak).
  Root: vac (class 2)
• gaganāpagā – Sky-river, celestial Ganges.
  noun (feminine)
  Compound of `gagana` (sky) + `apagā` (river).

Note: This is a long descriptive compound adjective modifying an implied neuter noun like 'puram' (city) or 'rājyam' (kingdom) in the accusative case.

उत्तराभ्दितटायातदूतवर्णितगुह्यकम् (uttarābhditaṭāyātadūtavarṇitaguhyakam) - Indicating the extent of knowledge and connections of the kingdom, reaching far northern regions and encompassing descriptions of semi-divine beings. (Where the Guhyakas were described by messengers arriving from the northern ocean shore.)

(adjective)

Accusative, neuter, singular of uttarābhditaṭāyātadūtavarṇitaguhyaka

uttarābhditaṭāyātadūtavarṇitaguhyaka - Having Guhyakas described by messengers who arrived from the northern ocean shore.

Compound type : Bahuvrīhi (uttara+abdhi+taṭa+āyāta+dūta+varṇita+guhyaka)

• uttara – Northern, upper, later.
  adjective (neuter)
• abdhi – Ocean, sea.
  noun (masculine)
• taṭa – Shore, bank, edge.
  noun (masculine)
• āyāta – Arrived, come.
  adjective (masculine)
  Past Passive Participle
  Derived from verb root `yā` (to go) with prefix `ā-`.
  Prefix: ā
  Root: yā (class 2)
• dūta – Messenger, envoy, ambassador.
  noun (masculine)
• varṇita – Described, depicted, praised, stated.
  adjective (masculine)
  Past Passive Participle
  Derived from verb root `varṇ` (to describe, color).
  Root: varṇ (class 10)
• guhyaka – A class of semi-divine beings, attendants of Kubera, often associated with hidden treasures or secrets.
  noun (masculine)

Note: This is a long descriptive compound adjective modifying an implied neuter noun like 'puram' (city) or 'rājyam' (kingdom) in the accusative case.