योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-78, verse-2

गङ्गाप्रवाहपतितधारापातविवर्धितः ।
सरित्सहस्रैः सहसा मेरुमन्दरभासुरैः ॥ २ ॥

gaṅgāpravāhapatitadhārāpātavivardhitaḥ ,
saritsahasraiḥ sahasā merumandarabhāsuraiḥ 2

2. gaṅgāpravāhapatitadhārāpātavivardhitaḥ
saritsahasraiḥ sahasā merumandarabhasuraiḥ

2. (saḥ jaḍavegaḥ) gaṅgāpravāhapatitadhārāpātavivardhitaḥ (abhūt),
sahasā merumandarabhasuraiḥ saritsahasraiḥ (ca).

2. It (the current) was increased by the falling torrents that plunged into the Gaṅgā's stream, along with thousands of other rivers, suddenly shining like Mount Meru and Mandara.

Words meanings summery:

• गङ्गाप्रवाहपतितधारापातविवर्धितः (gaṅgāpravāhapatitadhārāpātavivardhitaḥ) - increased by the falling torrents that plunged into the Gaṅgā's current

• सरित्सहस्रैः (saritsahasraiḥ) - by thousands of rivers

• सहसा (sahasā) - suddenly, forcefully, violently

• मेरुमन्दरभसुरैः (merumandarabhasuraiḥ) - shining like Mount Meru and Mandara

Words meanings and morphology

गङ्गाप्रवाहपतितधारापातविवर्धितः (gaṅgāpravāhapatitadhārāpātavivardhitaḥ) - increased by the falling torrents that plunged into the Gaṅgā's current

(adjective)

Nominative, masculine, singular of gaṅgāpravāhapatitadhārāpātavivardhita

gaṅgāpravāhapatitadhārāpātavivardhita - increased by the falling streams that fell into the Gaṅgā's current

Compound type : tatpurusha (gaṅgāpravāhapatita+dhārāpāta+vivardhita)

• gaṅgāpravāhapatita – fallen into the Gaṅgā's current
  adjective (masculine)
  Past Passive Participle (for patita)
• dhārāpāta – falling stream, torrent of water
  noun (masculine)
• vivardhita – increased, augmented, nourished
  adjective (masculine)
  Past Passive Participle
  Derived from root vṛdh (to grow, increase) with prefix vi-
  Prefix: vi
  Root: vṛdh (class 1)

सरित्सहस्रैः (saritsahasraiḥ) - by thousands of rivers

(noun)

Instrumental, neuter, plural of saritsahasra

saritsahasra - a thousand rivers

Compound type : tatpurusha (sarit+sahasra)

• sarit – river, stream
  noun (feminine)
• sahasra – a thousand
  noun (neuter)

सहसा (sahasā) - suddenly, forcefully, violently

(indeclinable)

मेरुमन्दरभसुरैः (merumandarabhasuraiḥ) - shining like Mount Meru and Mandara

(adjective)

Instrumental, neuter, plural of merumandarabhasura

merumandarabhasura - shining like Meru and Mandara (mountains)

Compound type : bahuvrihi (meru+mandara+bhasura)

• meru – Mount Meru, a mythical mountain
  proper noun (masculine)
• mandara – Mount Mandara, a mythical mountain
  proper noun (masculine)
• bhasura – shining, bright, radiant
  adjective (masculine)
  Root: bhās (class 1)