महाभारतः mahābhārataḥ - book-10, chapter-12, verse-4

यत्तदाचष्ट पुत्राय द्रोणः परपुरंजयः ।
अस्त्रं ब्रह्मशिरो नाम दहेद्यत्पृथिवीमपि ॥४॥

4. yattadācaṣṭa putrāya droṇaḥ parapuraṁjayaḥ ,
astraṁ brahmaśiro nāma dahedyatpṛthivīmapi.

4. yat tadā ācaṣṭa putrāya droṇaḥ parapurañjayaḥ
astram brahmaśiras nāma dahet yat pṛthivīm api

4. parapurañjayaḥ droṇaḥ tadā putrāya brahmaśiras nāma astram ācaṣṭa,
yat pṛthivīm api dahet.

4. Drona, the conqueror of enemy cities, then taught his son about the weapon named Brahmasiras, which has the power to incinerate even the entire earth.

Words meanings summery:

• यत् (yat) - Referring to the weapon that Drona taught. (which, that, what)

• तदा (tadā) - then, at that time

• आचष्ट (ācaṣṭa) - Drona taught his son. (he taught, he declared, he said)

• पुत्राय (putrāya) - To Ashvatthama, Drona's son. (to the son, for the son)

• द्रोणः (droṇaḥ) - Drona, the teacher of the Pandavas and Kauravas. (Drona)

• परपुरञ्जयः (parapurañjayaḥ) - An epithet for Drona, highlighting his martial prowess. (conqueror of enemy cities)

• अस्त्रम् (astram) - The Brahmasiras weapon. (weapon, missile)

• ब्रह्मशिरस् (brahmaśiras) - A powerful divine weapon. (Brahmasiras (name of a weapon))

• नाम (nāma) - 'named Brahmasiras' (named, by name, indeed)

• दहेत् (dahet) - Referring to the power of the Brahmasiras weapon. (it would burn, it might burn, it should burn)

• यत् (yat) - Connects to 'dahet' describing the weapon. (which, that, because)

• पृथिवीम् (pṛthivīm) - The entire planet Earth. (the earth)

• अपि (api) - Emphasizes the destructive power: 'even the earth'. (even, also, too)

Words meanings and morphology

यत् (yat) - Referring to the weapon that Drona taught. (which, that, what)

(pronoun)

neuter, singular of yad

yad - which, what, that

Note: The form 'yat' can be nominative or accusative singular neuter.

तदा (tadā) - then, at that time

(indeclinable)

आचष्ट (ācaṣṭa) - Drona taught his son. (he taught, he declared, he said)

(verb)

3rd person , singular, middle, imperfect (laṅ) of ācaṣṭa

Imperfect (Laṅ)

Imperfect, 3rd person singular, middle voice (ātmanepada), from root 'vac' with upasarga 'ā'.

Prefix: ā

Root: vac (class 2)

पुत्राय (putrāya) - To Ashvatthama, Drona's son. (to the son, for the son)

(noun)

Dative, masculine, singular of putra

putra - son, child

द्रोणः (droṇaḥ) - Drona, the teacher of the Pandavas and Kauravas. (Drona)

(proper noun)

Nominative, masculine, singular of droṇa

droṇa - Drona (proper name), a measure, a kind of vessel

Root: dru (class 1)

Note: The subject of the verb 'ācaṣṭa'.

परपुरञ्जयः (parapurañjayaḥ) - An epithet for Drona, highlighting his martial prowess. (conqueror of enemy cities)

(adjective)

Nominative, masculine, singular of parapurañjaya

parapurañjaya - conqueror of hostile cities

Compound type : tatpuruṣa (para+pura+jaya)

• para – other, hostile, enemy
  adjective (masculine)
• pura – city, fortress, town
  noun (neuter)
• jaya – victory, conquest, victorious
  noun (masculine)
  From root 'ji' (to conquer).
  Root: ji (class 1)

Note: Agrees with 'droṇaḥ'.

अस्त्रम् (astram) - The Brahmasiras weapon. (weapon, missile)

(noun)

Accusative, neuter, singular of astra

astra - weapon, missile, dart

Root: as (class 4)

Note: Object of 'ācaṣṭa' (taught).

ब्रह्मशिरस् (brahmaśiras) - A powerful divine weapon. (Brahmasiras (name of a weapon))

(proper noun)

neuter, singular of brahmaśiras

brahmaśiras - Brahmasiras (the head of Brahma), a powerful divine weapon

Compound type : tatpuruṣa (brahman+śiras)

• brahman – Brahma (the creator god), sacred utterance, the Absolute (brahman)
  noun (neuter)
  Root: bṛh (class 1)
• śiras – head, top, peak
  noun (neuter)

Note: The form 'brahmaśiras' here is an adjective to 'astram' (implied) or directly part of the name. It functions as a nominative or accusative.

नाम (nāma) - 'named Brahmasiras' (named, by name, indeed)

(indeclinable)

Note: Used as an indeclinable particle here.

दहेत् (dahet) - Referring to the power of the Brahmasiras weapon. (it would burn, it might burn, it should burn)

(verb)

3rd person , singular, active, optative (liṅ) of dah

Optative (Liṅ)

Optative mood, 3rd person singular, active voice.

Root: dah (class 1)

यत् (yat) - Connects to 'dahet' describing the weapon. (which, that, because)

(pronoun)

Nominative, neuter, singular of yad

yad - which, what, that, because

Note: The form 'yat' can be nominative or accusative singular neuter. Here as the subject of 'dahet'.

पृथिवीम् (pṛthivīm) - The entire planet Earth. (the earth)

(noun)

Accusative, feminine, singular of pṛthivī

pṛthivī - earth, ground, land

Root: pṛth

Note: Object of 'dahet'.

अपि (api) - Emphasizes the destructive power: 'even the earth'. (even, also, too)

(indeclinable)