वाल्मीकि-रामायणम् vālmīki-rāmāyaṇam - book-1, chapter-18, verse-4

अहं नियममातिष्ठ सिद्ध्यर्थं पुरुषर्षभ ।
तस्य विघ्नकरौ द्वौ तु राक्षसौ कामरूपिणौ ॥४॥

4. ahaṃ niyamamātiṣṭha siddhyarthaṃ puruṣarṣabha ,
tasya vighnakarau dvau tu rākṣasau kāmarūpiṇau.

4. aham niyamam ātiṣṭha siddhyartham puruṣarṣabha
tasya vighnakarau dvau tu rākṣasau kāmarūpiṇau

4. puruṣarṣabha aham siddhyartham niyamam ātiṣṭha
tu tasya vighnakarau dvau kāmarūpiṇau rākṣasau

4. O best among men, I am observing a vow for its accomplishment. However, two Rākṣasas, who can change their form at will, create obstacles for it.

Words meanings summery:

• अहम् (aham) - I

• नियमम् (niyamam) - vow, rule, observance

• आतिष्ठ (ātiṣṭha) - I am observing, I undertake

• सिद्ध्यर्थम् (siddhyartham) - for the purpose of accomplishment, for success

• पुरुषर्षभ (puruṣarṣabha) - O best among men

• तस्य (tasya) - for that vow (its, for it, of that)

• विघ्नकरौ (vighnakarau) - creating obstacles, obstructors

• द्वौ (dvau) - two

• तु (tu) - but, indeed, on the other hand

• राक्षसौ (rākṣasau) - Rākṣasas (demons)

• कामरूपिणौ (kāmarūpiṇau) - able to change form at will, shape-shifters

Words meanings and morphology

अहम् (aham) - I

(pronoun)

Nominative, singular of aham

aham - I

नियमम् (niyamam) - vow, rule, observance

(noun)

Accusative, masculine, singular of niyama

niyama - rule, self-restraint, vow, observance

Prefix: ni

Root: yam (class 1)

आतिष्ठ (ātiṣṭha) - I am observing, I undertake

(verb)

1st person , singular, active, present (laṭ) of sthā

Prefix: ā

Root: sthā (class 1)

सिद्ध्यर्थम् (siddhyartham) - for the purpose of accomplishment, for success

(indeclinable)

Compound type : tatpuruṣa (siddhi+artha)

• siddhi – accomplishment, success, attainment
  noun (feminine)
  Root: sidh (class 4)
• artha – purpose, meaning, wealth, object
  noun (masculine)

Note: Used adverbially.

पुरुषर्षभ (puruṣarṣabha) - O best among men

(noun)

Vocative, masculine, singular of puruṣarṣabha

puruṣarṣabha - best among men, bull among men

Compound type : tatpuruṣa (puruṣa+ṛṣabha)

• puruṣa – man, person, male, cosmic person
  noun (masculine)
• ṛṣabha – bull, chief, best
  noun (masculine)

तस्य (tasya) - for that vow (its, for it, of that)

(pronoun)

Genitive, masculine, singular of tad

tad - that, he, she, it

Note: Refers to 'niyamam' (vow).

विघ्नकरौ (vighnakarau) - creating obstacles, obstructors

(adjective)

Nominative, masculine, dual of vighnakara

vighnakara - obstacle-maker, obstructer

Compound type : tatpuruṣa (vighna+kara)

• vighna – obstacle, impediment
  noun (masculine)
  Prefix: vi
• kara – making, doing, causing
  adjective (masculine)
  Agent Noun
  Derived from root kṛ (to do, make)
  Root: kṛ (class 8)

Note: Modifies 'rākṣasau'.

द्वौ (dvau) - two

(numeral)

Note: Refers to 'rākṣasau'.

तु (tu) - but, indeed, on the other hand

(indeclinable)

Note: Conjunction.

राक्षसौ (rākṣasau) - Rākṣasas (demons)

(noun)

Nominative, masculine, dual of rākṣasa

rākṣasa - demon, evil spirit, a class of mythological beings

Note: Subject of the implied sentence.

कामरूपिणौ (kāmarūpiṇau) - able to change form at will, shape-shifters

(adjective)

Nominative, masculine, dual of kāmarūpin

kāmarūpin - assuming any shape at will

Compound type : bahuvrīhi (kāma+rūpa+in)

• kāma – desire, will, wish
  noun (masculine)
  Root: kam (class 1)
• rūpa – form, shape, appearance
  noun (neuter)
• in – possessing, having (suffix)
  suffix
  Taddhita suffix forming possessive adjective

Note: Modifies 'rākṣasau'.