वाल्मीकि-रामायणम् vālmīki-rāmāyaṇam - book-7, chapter-20, verse-13

ततो लोकत्रयं जित्वा स्थाप्य नागान् सुरान् वशे ।
समुद्रममृतार्थं वै मथिष्यामि रसालयम् ॥१३॥

13. tato lokatrayaṃ jitvā sthāpya nāgān surān vaśe ,
samudramamṛtārthaṃ vai mathiṣyāmi rasālayam.

13. tataḥ lokatrayam jitvā sthāpya nāgān surān vaśe
| samudram amṛtārtham vai mathiṣyāmi rasālayam

13. tataḥ lokatrayam jitvā nāgān surān vaśe sthāpya
amṛtārtham vai rasālayam samudram mathiṣyāmi

13. Then, having conquered the three worlds and brought the nāgas and gods under control, I will certainly churn the ocean, the abode of waters, to obtain the ambrosia.

Words meanings summery:

• ततः (tataḥ) - then (then, thereafter, from that)

• लोकत्रयम् (lokatrayam) - the three worlds (heaven, earth, and netherworld) (the three worlds)

• जित्वा (jitvā) - having conquered (having conquered, having won)

• स्थाप्य (sthāpya) - having placed (having placed, having established, having caused to stand)

• नागान् (nāgān) - the nāgas (serpent deities) (serpents, elephants, mountain-dwellers)

• सुरान् (surān) - the gods (gods, deities)

• वशे (vaśe) - under control (in control, under power, in one's will)

• समुद्रम् (samudram) - the ocean (ocean, sea)

• अमृतार्थम् (amṛtārtham) - for the sake of ambrosia (for the sake of ambrosia, for immortality)

• वै (vai) - certainly (indeed, certainly, surely)

• मथिष्यामि (mathiṣyāmi) - I will churn (I will churn, I will agitate)

• रसालयम् (rasālayam) - the abode of waters (the ocean) (abode of waters, ocean, source of sap/juice)

Words meanings and morphology

ततः (tataḥ) - then (then, thereafter, from that)

(indeclinable)

derived from tad (that) + -tas suffix

लोकत्रयम् (lokatrayam) - the three worlds (heaven, earth, and netherworld) (the three worlds)

(noun)

Accusative, neuter, singular of lokatraya

lokatraya - the three worlds (heaven, earth, and netherworld)

Compound type : tatpuruṣa (loka+traya)

• loka – world, realm, people
  noun (masculine)
• traya – group of three, triad
  noun (neuter)

जित्वा (jitvā) - having conquered (having conquered, having won)

(indeclinable)

absolutive / gerund

formed from root √ji (to conquer, to win) with suffix -tvā

Root: ji (class 1)

स्थाप्य (sthāpya) - having placed (having placed, having established, having caused to stand)

(indeclinable)

absolutive / gerund (causative)

formed from causative stem of root √sthā (to stand) with suffix -ya (functioning as an absolutive)

Root: sthā (class 1)

नागान् (nāgān) - the nāgas (serpent deities) (serpents, elephants, mountain-dwellers)

(noun)

Accusative, masculine, plural of nāga

nāga - serpent, cobra, elephant, a mountain

सुरान् (surān) - the gods (gods, deities)

(noun)

Accusative, masculine, plural of sura

sura - god, deity

वशे (vaśe) - under control (in control, under power, in one's will)

(noun)

Locative, masculine, singular of vaśa

vaśa - will, control, power, authority

Root: vaś

समुद्रम् (samudram) - the ocean (ocean, sea)

(noun)

Accusative, masculine, singular of samudra

samudra - ocean, sea

अमृतार्थम् (amṛtārtham) - for the sake of ambrosia (for the sake of ambrosia, for immortality)

(noun)

Accusative, masculine, singular of amṛtārtha

amṛtārtha - for the sake of ambrosia, for immortality

Compound type : tatpuruṣa (amṛta+artha)

• amṛta – immortality, ambrosia, nectar
  noun (neuter)
  Past Passive Participle
  Negation 'a-' + root √mṛ (to die) + -ta suffix
  Root: mṛ (class 6)
• artha – purpose, meaning, wealth, object, sake
  noun (masculine)

Note: Adverbial usage.

वै (vai) - certainly (indeed, certainly, surely)

(indeclinable)

मथिष्यामि (mathiṣyāmi) - I will churn (I will churn, I will agitate)

(verb)

1st person , singular, active, future (lṛṭ) of math

future tense, 1st person singular

from √math, s-future, parasmaipada

Root: math (class 1)

रसालयम् (rasālayam) - the abode of waters (the ocean) (abode of waters, ocean, source of sap/juice)

(noun)

Accusative, masculine, singular of rasālaya

rasālaya - abode of waters, ocean, repository of liquids/flavors

Compound type : tatpuruṣa (rasa+ālaya)

• rasa – water, fluid, juice, essence, taste, sentiment
  noun (masculine)
• ālaya – abode, dwelling, receptacle, house
  noun (masculine)
  From ā + √lī (to cling, to dissolve)
  Prefix: ā
  Root: lī (class 4)

Note: Appears to be in apposition to `samudram`.