योगवासिष्ठः yogavāsiṣṭhaḥ - book-6, chapter-81, verse-50

ब्रह्मनाडीप्रवाहेण शक्तिः कुण्डलिनी यदा ।
बहिरूर्ध्वं कपाटस्य द्वादशाङ्गुलमूर्धनि ॥ ५० ॥

brahmanāḍīpravāheṇa śaktiḥ kuṇḍalinī yadā ,
bahirūrdhvaṃ kapāṭasya dvādaśāṅgulamūrdhani 50

50. brahmanāḍīpravāheṇa śaktiḥ kuṇḍalinī yadā
bahiḥ ūrdhvam kapāṭasya dvādaśāṅgulam mūrdhani

50. yadā kuṇḍalinī śaktiḥ brahmanāḍīpravāheṇa
kapāṭasya mūrdhani bahiḥ ūrdhvam dvādaśāṅgulam

50. When the Kuṇḍalinī (kuṇḍalinī) śakti, through the flow of the Brahman-nāḍī (brahman-nāḍī), rises upwards, beyond the aperture (kapāṭa) and twelve finger-breadths above the crown of the head (mūrdhan)...

Words meanings summery:

• ब्रह्मनाडीप्रवाहेण (brahmanāḍīpravāheṇa) - by the flow of the Brahman-nāḍī (brahman-nāḍī)

• शक्तिः (śaktiḥ) - power (śakti), energy, force

• कुण्डलिनी (kuṇḍalinī) - the Kuṇḍalinī (kuṇḍalinī) power

• यदा (yadā) - when

• बहिः (bahiḥ) - outside, outwardly, beyond

• ऊर्ध्वम् (ūrdhvam) - upwards, above, aloft

• कपाटस्य (kapāṭasya) - of the aperture (kapāṭa) at the crown of the head (Brahmarandhra) (of the door, of the aperture)

• द्वादशाङ्गुलम् (dvādaśāṅgulam) - a distance of twelve finger-breadths (twelve finger-breadths)

• मूर्धनि (mūrdhani) - at the crown of the head (mūrdhan) (on the head, at the crown)

Words meanings and morphology

ब्रह्मनाडीप्रवाहेण (brahmanāḍīpravāheṇa) - by the flow of the Brahman-nāḍī (brahman-nāḍī)

(noun)

Instrumental, masculine, singular of brahmanāḍīpravāha

brahmanāḍīpravāha - flow of the Brahman-nāḍī

Compound type : tatpuruṣa (brahmanāḍī+pravāha)

• brahmanāḍī – the central subtle energy channel (nāḍī) associated with Brahman
  noun (feminine)
• pravāha – flow, stream, current
  noun (masculine)
  From root 'vah' with prefix 'pra'
  Prefix: pra
  Root: vah (class 1)

Note: Means by which Kuṇḍalinī moves.

शक्तिः (śaktiḥ) - power (śakti), energy, force

(noun)

Nominative, feminine, singular of śakti

śakti - power, energy, force, faculty, divine feminine principle

From root 'śak' (to be able)

Root: śak (class 5)

Note: Predicate noun for Kuṇḍalinī.

कुण्डलिनी (kuṇḍalinī) - the Kuṇḍalinī (kuṇḍalinī) power

(proper noun)

Nominative, feminine, singular of kuṇḍalinī

kuṇḍalinī - Kundalini (kuṇḍalinī), the coiled primordial energy in the subtle body

Feminine form of 'kuṇḍalin' (coiled one)

Note: Subject of the sentence.

यदा (yadā) - when

(indeclinable)

Note: Introduces a temporal clause.

बहिः (bahiḥ) - outside, outwardly, beyond

(indeclinable)

Note: Adverb of place/direction.

ऊर्ध्वम् (ūrdhvam) - upwards, above, aloft

(indeclinable)

Note: Adverb of place/direction.

कपाटस्य (kapāṭasya) - of the aperture (kapāṭa) at the crown of the head (Brahmarandhra) (of the door, of the aperture)

(noun)

Genitive, masculine, singular of kapāṭa

kapāṭa - door, gate, shutter, aperture, valve

Note: Denotes possession or relation to 'mūrdhani'.

द्वादशाङ्गुलम् (dvādaśāṅgulam) - a distance of twelve finger-breadths (twelve finger-breadths)

(adjective)

Accusative, neuter, singular of dvādaśāṅgula

dvādaśāṅgula - measuring twelve finger-breadths

Compound type : tatpuruṣa (dvādaśan+aṅgula)

• dvādaśan – twelve
  numeral
• aṅgula – finger, finger-breadth (unit of measure)
  noun (neuter)

Note: Adverbial accusative of measure, indicating distance.

मूर्धनि (mūrdhani) - at the crown of the head (mūrdhan) (on the head, at the crown)

(noun)

Locative, masculine, singular of mūrdhan

mūrdhan - head, skull, crown, top

Note: Indicates location.