महाभारतः mahābhārataḥ - book-6, chapter-115, verse-13

अयं पितरमाज्ञाय कामार्तं शंतनुं पुरा ।
ऊर्ध्वरेतसमात्मानं चकार पुरुषर्षभः ॥१३॥

13. ayaṁ pitaramājñāya kāmārtaṁ śaṁtanuṁ purā ,
ūrdhvaretasamātmānaṁ cakāra puruṣarṣabhaḥ.

13. ayam pitaram ājñāya kāmārtam śaṃtanum purā
ūrdhvaretasam ātmānam cakāra puruṣarṣabhaḥ

13. purā ayam puruṣarṣabhaḥ kāmārtam śaṃtanum
pitaram ājñāya ātmānam ūrdhvaretasam cakāra

13. Formerly, this best among men (puruṣarṣabha), understanding his father Shantanu to be distressed by desire (kāmārta), made himself celibate (ūrdhvaretas).

Words meanings summery:

• अयम् (ayam) - this, this one

• पितरम् (pitaram) - father

• आज्ञाय (ājñāya) - having known, having understood, having perceived

• कामार्तम् (kāmārtam) - distressed by desire, afflicted by love

• शंतनुम् (śaṁtanum) - Shantanu

• पुरा (purā) - formerly, in the past, anciently

• ऊर्ध्वरेतसम् (ūrdhvaretasam) - celibate, continent; one whose semen flows upwards

• आत्मानम् (ātmānam) - himself, the self (ātman)

• चकार (cakāra) - made, did, performed

• पुरुषर्षभः (puruṣarṣabhaḥ) - bull among men, best among men

Words meanings and morphology

अयम् (ayam) - this, this one

(pronoun)

Nominative, masculine, singular of idam

idam - this, this one

पितरम् (pitaram) - father

(noun)

Accusative, masculine, singular of pitṛ

pitṛ - father, ancestor

आज्ञाय (ājñāya) - having known, having understood, having perceived

(indeclinable)

Absolutive (Gerund)

Formed by adding -ya to the root with prefix ā-.

Prefix: ā

Root: √jñā (class 9)

कामार्तम् (kāmārtam) - distressed by desire, afflicted by love

(adjective)

Accusative, masculine, singular of kāmārta

kāmārta - distressed by desire, suffering from love

Compound type : Tatpurusha (kāma+ārta)

• kāma – desire, wish, love
  noun (masculine)
  Root: √kam (class 1)
• ārta – distressed, afflicted, suffering
  adjective
  Past Passive Participle
  From √ṛ (to go, move, rise; also to suffer).
  Root: √ṛ (class 1)

Note: Modifies 'śaṃtanum'.

शंतनुम् (śaṁtanum) - Shantanu

(proper noun)

Accusative, masculine, singular of śaṃtanu

śaṁtanu - Shantanu (proper name of a king, Bhishma's father)

पुरा (purā) - formerly, in the past, anciently

(indeclinable)

ऊर्ध्वरेतसम् (ūrdhvaretasam) - celibate, continent; one whose semen flows upwards

(adjective)

Accusative, masculine, singular of ūrdhvaretas

ūrdhvaretas - having the semen flowing upwards, continent, chaste, celibate

Compound type : Bahuvrīhi (ūrdhva+retas)

• ūrdhva – upward, elevated, high
  adjective
• retas – semen, virile fluid, seed, vital essence
  noun (neuter)
  Root: √rī (class 4)

Note: Modifies 'ātmānam'.

आत्मानम् (ātmānam) - himself, the self (ātman)

(noun)

Accusative, masculine, singular of ātman

ātman - self, soul, spirit, essence, ego (ātman)

Note: Used reflexively here.

चकार (cakāra) - made, did, performed

(verb)

3rd person , singular, active, perfect (liṭ) of √kṛ

Root: √kṛ (class 8)

पुरुषर्षभः (puruṣarṣabhaḥ) - bull among men, best among men

(noun)

Nominative, masculine, singular of puruṣarṣabha

puruṣarṣabha - bull among men, best of men, eminent person (puruṣa)

Compound type : Tatpurusha (puruṣa+ṛṣabha)

• puruṣa – man, person; the supreme cosmic person (puruṣa)
  noun (masculine)
• ṛṣabha – bull; best, chief, excellent
  noun (masculine)

Note: Refers to Bhishma.