Pranayama is a Sanskrit

Sanskrit

Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...

 word meaning "extension of the prana or breath" or more accurately, "extension of the life force". The word is composed of two Sanskrit words, Prāna

Prana

Prana is the Sanskrit word for "vital life" .It is one of the five organs of vitality or sensation, viz. prana "breath", vac "speech", chakshus "sight", shrotra "hearing", and manas "thought" Prana is the Sanskrit word for "vital life" (from the root "to fill", cognate to Latin plenus...

, life force, or vital energy, particularly, the breath, and "āyāma", to extend, draw out, restrain, or control.
Pranayama (Devanagari

Devanagari

Devanagari |deva]]" and "nāgarī" ), also called Nagari , is an abugida alphabet of India and Nepal...

: , ) is a Sanskrit compound.

V. S. Apte provides fourteen different meanings for the word prana (Devanagari

Devanagari

Devanagari |deva]]" and "nāgarī" ), also called Nagari , is an abugida alphabet of India and Nepal...

: , ) including these:

• Breath, respiration
• The breath of life, vital air, principle of life (usually plural in this sense, there being five such vital airs generally assumed, but three, six, seven, nine, and even ten are also spoken of)
• Energy, vigor
• The spirit or soul

Of these meanings, the concept of "vital air" is used by Bhattacharyya to describe the concept as used in Sanskrit texts dealing with pranayama.