In philosophy and religion, spirit is the vital principle or animating essence within humans or, in some views, all living things. Although views of spirit vary between different belief systems, when spirit is contrasted with the soul, the former is often seen as a basic natural force, principle or substance, whereas the latter is used to described the organized structure of an individual being's consciousness, in humans including their personality. Spirit as a substance may also be contrasted with matter, where it is usually seen as more subtle, an idea put forth for example in the Principia Mathematica.
The word spirit came into Middle English via Old French esperit. Its source is Latin spīritus, whose original meaning was "breath, breathing" and hence "spirit, soul, courage, vigor"; its ultimate origin is a Proto-Indo-European root .
In Latin, spīritus was distinct from Latin anima, whose etymological meaning was also "breathing" (PIE root *h2enh1-), yet which had taken a slightly different meaning, namely "soul".
The distinction between "soul" and "spirit" in English mirrors that between "psykhē" and "pneuma" in Classical Greek, with both words having a connection to breathing:
(ψυχή), originally "cold air", hence "breath of life" and "soul" (PIE root "to breathe").
(πνεῦμα) "breath, motile air, spirit", from verb (πνέω) "to breathe".
A distinction between soul and spirit also developed in the Abrahamic religions: Arabic (نفس) opposite (روح); Hebrew neshama ( ) or nephesh ( ) (in Hebrew comes from the root or "breath") opposite ( ). (Note, however, that in Semitic just as in Indo-European, this dichotomy has not always been as neat historically as it has come to be taken over a long period of development: Both (root ) and (root ), as well as cognate words in various Semitic languages, including Arabic, also preserve meanings involving miscellaneous air phenomena: "breath", "wind", and even "odour".)
Ruach HaKodesh
Similar concepts in other languages include Chinese Ling and hun (靈魂) and Sanskrit akasha / atman (see also prana).