The term spirit translates from Greek 'pneuma' and Hebrew 'ruach'. It is a translation that today we must consider, however, partly because 'pneuma' and 'ruach', both in antiquity meant, while spirit, literally air, the simple and common air of nature. From Greek 'pneuma' comes, for example, something so far from any form of spirituality as the word ‘pneumatic’. Air and spirit are very different things for us, radically different we must say in our modern languages, but curiously were interchangeable in ancient Greek and Hebrew. What is now a marked double meaning was originally a complete identity of both concepts.
The Latin 'spiritus', besides referring to what we mean by spirit, also meant air or 'air breathing' or breath, invariably as the Greek and Hebrew words we have seen. 'Spiritus' is the root of words related to both modern meanings as are spirituality, respiration, inspire and expire.
Neither escapes of the standard the Latin word for soul. 'Anemos', besides the sense of soul, means blow, breath, wind. Hence, for example, the word anemometer, which refers to the apparatus used to measure the intensity of the wind. The Latin 'anemos', as the spirit, is the breath of life, the basis of life, because breath is the proof that one is alive, common to animals and people.
The Arab 'ruh' well just have a sense of spirit or soul, while one of wind or air.
Similarly, the Hindu notion of 'prana', which means breath, in Sanskrit means 'primary and all round Life Energy'. 'Prana' is described in the Upanishads as a physical principle of air that permeates all forms of life, which is life maintainer of body and also, at the same time, is the origin of the variable thought. It occurs mainly through breath (although the blood and other fluids). In Ayurveda, tantra and Tibetan medicine ‘prana vayu’ is the basic ‘vayu’ (that is: wind, air) from which all the other vayus arise. “Prana vayu” is beating of the heart and breathing. Prana enters the body through the breath and is sent to every cell through the circulatory system.
In Chinese medicine, especially acupuncture and its derivations, the equivalent of prana is qi. Qi is literally breath and mood, is an active principle forming part of any living thing which has to be understood as a ‘vital energy flow’. Qi is an air energy that continuously flows by nature, and a disruption of its free flow in the body is the basis of physical and psychological disorders.
The Hindu word for soul, 'atman' in Sanskrit means breath again. In Hindu thought, the 'atman' originally was the 'breath of life' or 'life principle' of living beings. Later, on one hand, takes the modern sense westernmost 'inner reality' or 'inner self', but on the other side, especially from the Upanishads, the 'atman' is increasingly identified with the 'brahman', the absolute that penetrates and surrounds all beings.
Atman
"Brahman, Self, Purusha, Chaitanya, Consciousness, God, Atman, Immortality, Freedom, Perfection, Bliss, Bhuma or the unconditioned are synonymous terms." - Swami Sivananva
Atman as "self" refers to a state of being "unconditioned," which is related to the Absolute, the Ain Soph, or the Shunyata (Emptiness). Thus, Atman refers to the Innermost, the Spirit, the Son of God, who longs to return to that which is beyond words.
"Atman, in Himself, is the ineffable Being, the one who is beyond time and eternity, without end of days. He does not die, neither reincarnates (the ego is what returns), but Atman is absolutely perfect." - Samael Aun Weor.
"The Being Himself is Atman, the Ineffable. If we commit the error of giving the Being the qualifications of superior “I,” alter ego, subliminal “I,” or divine ego, etc., we commit blasphemy, because That which is Divine, the Reality, can never fall into the heresy of separability. Superior and inferior are two sections of the same thing. Superior “I” or inferior “I” are two sections of the same pluralized ego (Satan). The Being is the Being, and the reason for the Being to be is to be the same Being. The Being transcends the personality, the “I,” and individuality." Samael Aun Weor.
The Atman is the common Consciousness in all beings. A thief, a prostitute, a scavenger, a king, a rogue, a saint, a dog, a cat, a rat-all have the same common Atman.
"The Atman is common to all. It is not an individual's sole registered property. The Atman is the one amidst the many. It is constant amidst the forms which come and go. It is the pure, absolute, essential Consciousness of all the conscious beings. The source of all life, the source of all knowledge is the Atman, thy innermost Self. This Atman or Supreme Soul is transcendent, inexpressible, uninferable, unthinkable, indescribable, the ever-peaceful, all-blissful. There is no difference between the Atman and bliss. The Atman is bliss itself. God, perfection, peace, immortality, bliss are one. The goal of life is to attain perfection, immortality or God. The nearer one approaches the Truth, the happier one becomes. For, the essential nature of Truth is positive, absolute bliss. There is no bliss in the finite. Bliss is only in the Infinite. Eternal bliss can be had only from the eternal Self. To know the Self is to enjoy eternal bliss and everlasting peace. Self-realisation bestows eternal existence, absolute knowledge, and perennial bliss. None can be saved without Self-realisation." - Swami Sivananda