महाभारतः mahābhārataḥ - book-12, chapter-181, verse-18

पिशाचा राक्षसाः प्रेता बहुधा म्लेच्छजातयः ।
प्रनष्टज्ञानविज्ञानाः स्वच्छन्दाचारचेष्टिताः ॥१८॥

18. piśācā rākṣasāḥ pretā bahudhā mlecchajātayaḥ ,
pranaṣṭajñānavijñānāḥ svacchandācāraceṣṭitāḥ.

18. piśācāḥ rākṣasāḥ pretāḥ bahudhā mlecchajātayaḥ
pranaṣṭajñānavijñānāḥ svacchandācāraceṣṭitāḥ

18. piśācāḥ rākṣasāḥ pretāḥ mlecchajātayaḥ bahudhā
pranaṣṭajñānavijñānāḥ svacchandācāraceṣṭitāḥ

18. Goblins (piśācāḥ), demons (rākṣasāḥ), ghosts (pretāḥ), and various Mleccha races are those whose knowledge and wisdom are completely lost, and whose conduct and actions are driven by unrestrained self-will.

Words meanings summery:

• पिशाचाः (piśācāḥ) - goblins, fiends, demons

• राक्षसाः (rākṣasāḥ) - demons, evil spirits

• प्रेताः (pretāḥ) - ghosts, spirits of the dead, departed spirits

• बहुधा (bahudhā) - in many ways, manifold, various

• म्लेच्छजातयः (mlecchajātayaḥ) - Mleccha races, barbarian classes/species

• प्रनष्टज्ञानविज्ञानाः (pranaṣṭajñānavijñānāḥ) - whose knowledge and wisdom are lost/destroyed

• स्वच्छन्दाचारचेष्टिताः (svacchandācāraceṣṭitāḥ) - whose actions/conduct are self-willed/unrestrained

Words meanings and morphology

पिशाचाः (piśācāḥ) - goblins, fiends, demons

(noun)

Nominative, masculine, plural of piśāca

piśāca - a goblin, demon, fiend; a type of malevolent spirit

राक्षसाः (rākṣasāḥ) - demons, evil spirits

(noun)

Nominative, masculine, plural of rākṣasa

rākṣasa - a demon, evil spirit, ghoul, monster

Conventionally means 'one who harms/is harmful'.

Root: rakṣ (class 1)

प्रेताः (pretāḥ) - ghosts, spirits of the dead, departed spirits

(noun)

Nominative, masculine, plural of preta

preta - a departed spirit, ghost; deceased

Past Passive Participle

From pra-i (to go forth, die)

Prefix: pra

Root: i (class 2)

बहुधा (bahudhā) - in many ways, manifold, various

(indeclinable)

Suffix dhā added to bahu.

म्लेच्छजातयः (mlecchajātayaḥ) - Mleccha races, barbarian classes/species

(noun)

Nominative, feminine, plural of mlecchajāti

mlecchajāti - Mleccha race/class/species; barbarian group

Compound of Mleccha and Jāti.

Compound type : tatpuruṣa (mleccha+jāti)

• mleccha – a barbarian, foreigner; impure person
  noun (masculine)
• jāti – birth, race, lineage, class, species
  noun (feminine)
  Root: jan (class 4)

प्रनष्टज्ञानविज्ञानाः (pranaṣṭajñānavijñānāḥ) - whose knowledge and wisdom are lost/destroyed

(adjective)

Nominative, masculine, plural of pranaṣṭajñānavijñāna

pranaṣṭajñānavijñāna - having lost (all) knowledge and wisdom/discernment

Bahuvrihi compound: pranaṣṭaṃ jñānaṃ ca vijñānaṃ ca yeṣām te

Compound type : bahuvrīhi (pranaṣṭa+jñāna+vijñāna)

• pranaṣṭa – lost, destroyed, perished
  adjective
  Past Passive Participle
  From pra-naś (to perish, disappear)
  Prefix: pra
  Root: naś (class 4)
• jñāna – knowledge, spiritual knowledge, understanding
  noun (neuter)
  Root: jñā (class 9)
• vijñāna – discernment, specific knowledge, wisdom, science
  noun (neuter)
  Prefix: vi
  Root: jñā (class 9)

Note: Agreeing with the preceding nouns (piśācāḥ, rākṣasāḥ, pretāḥ, mlecchajātayaḥ).

स्वच्छन्दाचारचेष्टिताः (svacchandācāraceṣṭitāḥ) - whose actions/conduct are self-willed/unrestrained

(adjective)

Nominative, masculine, plural of svacchandācāraceṣṭita

svacchandācāraceṣṭita - whose conduct and actions are free-willed; behaving according to one's own will

Bahuvrihi compound: svacchandaḥ ācāraḥ ca ceṣṭitaṃ ca yeṣām te

Compound type : bahuvrīhi (svacchanda+ācāra+ceṣṭita)

• svacchanda – free-willed, independent, unrestrained
  adjective
  From sva (own) + chanda (will, desire)
• ācāra – conduct, custom, practice
  noun (masculine)
  From ā-car (to behave)
  Prefix: ā
  Root: car (class 1)
• ceṣṭita – action, deed, effort, behavior
  noun (neuter)
  Past Passive Participle
  From ceṣṭ (to move, act, endeavor)
  Root: ceṣṭ (class 1)

Note: Agreeing with the preceding nouns (piśācāḥ, rākṣasāḥ, pretāḥ, mlecchajātayaḥ).