महाभारतः mahābhārataḥ - book-13, chapter-109, verse-16

अष्टमीमथ कौन्तेय शुक्लपक्षे चतुर्दशीम् ।
उपोष्य व्याधिरहितो वीर्यवानभिजायते ॥१६॥

16. aṣṭamīmatha kaunteya śuklapakṣe caturdaśīm ,
upoṣya vyādhirahito vīryavānabhijāyate.

16. aṣṭamīm atha kaunteya śuklapakṣe caturdaśīm
upoṣya vyādhirahitaḥ vīryavān abhijāyate

16. kaunteya śuklapakṣe aṣṭamīm atha caturdaśīm
upoṣya vyādhirahitaḥ vīryavān abhijāyate

16. O son of Kuntī, one who fasts on the eighth and fourteenth lunar days of the bright half of the month is born free from disease and endowed with vigor.

Words meanings summery:

• अष्टमीम् (aṣṭamīm) - the eighth (lunar day)

• अथ (atha) - then, now, moreover

• कौन्तेय (kaunteya) - O Arjuna, son of Kuntī (O son of Kuntī)

• शुक्लपक्षे (śuklapakṣe) - in the bright half of the month, in the waxing fortnight

• चतुर्दशीम् (caturdaśīm) - the fourteenth (lunar day)

• उपोष्य (upoṣya) - having fasted, having observed a vow

• व्याधिरहितः (vyādhirahitaḥ) - free from disease, healthy

• वीर्यवान् (vīryavān) - endowed with valor/vigor, potent

• अभिजायते (abhijāyate) - is born, originates

Words meanings and morphology

अष्टमीम् (aṣṭamīm) - the eighth (lunar day)

(noun)

Accusative, feminine, singular of aṣṭamī

aṣṭamī - eighth (feminine), eighth lunar day

अथ (atha) - then, now, moreover

(indeclinable)

कौन्तेय (kaunteya) - O Arjuna, son of Kuntī (O son of Kuntī)

(proper noun)

Vocative, masculine, singular of kaunteya

kaunteya - son of Kuntī (e.g., Arjuna)

Patronymic from Kuntī

शुक्लपक्षे (śuklapakṣe) - in the bright half of the month, in the waxing fortnight

(noun)

Locative, masculine, singular of śuklapakṣa

śuklapakṣa - bright fortnight, waxing moon period

Compound type : tatpuruṣa (śukla+pakṣa)

• śukla – white, bright, pure
  adjective (masculine)
• pakṣa – half (of a lunar month), fortnight, side, wing
  noun (masculine)

चतुर्दशीम् (caturdaśīm) - the fourteenth (lunar day)

(noun)

Accusative, feminine, singular of caturdaśī

caturdaśī - fourteenth (feminine), fourteenth lunar day

उपोष्य (upoṣya) - having fasted, having observed a vow

(indeclinable)

Absolutive (Gerund)

From upa-vas with lyap suffix.

Prefix: upa

Root: vas (class 1)

व्याधिरहितः (vyādhirahitaḥ) - free from disease, healthy

(adjective)

Nominative, masculine, singular of vyādhirahita

vyādhirahita - free from disease

Compound type : tatpuruṣa (vyādhi+rahita)

• vyādhi – disease, sickness, ailment
  noun (masculine)
• rahita – free from, devoid of, abandoned
  adjective (masculine)
  Past Passive Participle
  From root rah (to abandon, to be devoid of)
  Root: rah (class 1)

वीर्यवान् (vīryavān) - endowed with valor/vigor, potent

(adjective)

Nominative, masculine, singular of vīryavat

vīryavat - strong, potent, vigorous, valorous

From vīrya (valor, strength) + -vat (possessive suffix)

अभिजायते (abhijāyate) - is born, originates

(verb)

3rd person , singular, middle, present indicative (laṭ) of abhijan

Prefix: abhi

Root: jan (class 4)