महाभारतः mahābhārataḥ - book-3, chapter-185, verse-5

अवाक्शिरास्तथा चापि नेत्रैरनिमिषैर्दृढम् ।
सोऽतप्यत तपो घोरं वर्षाणामयुतं तदा ॥५॥

5. avākśirāstathā cāpi netrairanimiṣairdṛḍham ,
so'tapyata tapo ghoraṁ varṣāṇāmayutaṁ tadā.

5. avākśirāḥ tathā ca api netraiḥ animiṣaiḥ dṛḍham
saḥ atapyata tapas ghoraṃ varṣāṇām ayutam tadā

5. And thus, with his head bowed downwards and with unblinking eyes, he then performed terrible asceticism (tapas) intensely for ten thousand years.

Words meanings summery:

• अवाक्शिराः (avākśirāḥ) - with head downwards, having a downward head

• तथा (tathā) - thus, so, in that manner

• च (ca) - and, also

• अपि (api) - even, also, too

• नेत्रैः (netraiḥ) - by eyes

• अनिमिषैः (animiṣaiḥ) - with unblinking (eyes)

• दृढम् (dṛḍham) - firmly, steadily, intensely, strongly

• सः (saḥ) - he, that

• अतप्यत (atapyata) - he performed austerity, he practiced penance, he heated himself

• तपस् (tapas) - austerity, penance

• घोरं (ghoraṁ) - terrible, dreadful, severe, fearful (accusative neuter)

• वर्षाणाम् (varṣāṇām) - of years, for years

• अयुतम् (ayutam) - ten thousand, an immense number

• तदा (tadā) - then, at that time

Words meanings and morphology

अवाक्शिराः (avākśirāḥ) - with head downwards, having a downward head

(adjective)

Nominative, masculine, singular of avākśiras

avākśiras - having the head downwards

compound of `avāk` (downwards) and `śiras` (head)

Compound type : bahuvrīhi (avāk+śiras)

• avāk – downwards, below
  indeclinable
• śiras – head, top
  noun (neuter)

Note: Agrees with the implied subject (Manu).

तथा (tathā) - thus, so, in that manner

(indeclinable)

च (ca) - and, also

(indeclinable)

अपि (api) - even, also, too

(indeclinable)

नेत्रैः (netraiḥ) - by eyes

(noun)

Instrumental, neuter, plural of netra

netra - eye, leading, guiding

Root: nī (class 1)

अनिमिषैः (animiṣaiḥ) - with unblinking (eyes)

(adjective)

Instrumental, neuter, plural of animiṣa

animiṣa - unblinking, not winking, steady

negation of `nimiṣa` (winking)

Compound type : nañ-tatpuruṣa (a+nimiṣa)

• a – not, un-
  indeclinable
• nimiṣa – winking, twinkling
  noun (masculine)
  Derived from root miṣ
  Prefix: ni
  Root: miṣ (class 6)

दृढम् (dṛḍham) - firmly, steadily, intensely, strongly

(indeclinable)

From root dṛh

Root: dṛh (class 7)

Note: Accusative singular neuter form used adverbially.

सः (saḥ) - he, that

(pronoun)

Nominative, masculine, singular of tad

tad - that, he, she, it

Note: Subject of `atapyata`.

अतप्यत (atapyata) - he performed austerity, he practiced penance, he heated himself

(verb)

3rd person , singular, middle, past imperfect (laṅ) of tap

imperfect middle

Imperfect form (laṅ) in middle voice. Implied subject is Manu.

Root: tap (class 1)

तपस् (tapas) - austerity, penance

(noun)

Accusative, neuter, singular of tapas

tapas - religious austerity, penance, spiritual fervor, heat

Root: tap (class 1)

Note: Object of `atapyata`.

घोरं (ghoraṁ) - terrible, dreadful, severe, fearful (accusative neuter)

(adjective)

Accusative, neuter, singular of ghora

ghora - terrible, dreadful, fearful, intense, severe

Root: ghur

वर्षाणाम् (varṣāṇām) - of years, for years

(noun)

Genitive, neuter, plural of varṣa

varṣa - year, rain, monsoon

Root: vṛṣ (class 1)

Note: Expresses duration here.

अयुतम् (ayutam) - ten thousand, an immense number

(numeral)

Note: Accusative indicating extent/duration (like `varṣāṇām` as a whole phrase).

तदा (tadā) - then, at that time

(indeclinable)

derived from `tad` (that) + `dā` suffix