Caution: Although Crosswalk is usually a reliable source of information, these particular definitions from Crosswalk have been found to contain some theological errors which, if believed, could be fatal. Other lesser theological errors are also know to exist in some of these definitions. The correctness of still other definitions is uncertain. All in all, caution is advised in the use of any of these Crosswalk definitions for this particular word. A similar caution is also advised in the instances of some definitions for other words, notably for the word "soul". See also the comments below the last definition.

1. the third person of the triune God, the Holy Spirit, coequal, coeternal with the Father and the Son
   1.a] sometimes referred to in a way which emphasizes his personality and character (the Holy Spirit)
   1.b] sometimes referred to in a way which emphasizes his work and power (the Spirit of Truth)
   1.c] never referred to as a depersonalized force
2. the spirit, i.e. the vital principal by which the body is animated
   2.a] the rational spirit, the power by which the human being feels, thinks, decides
   2.b] the soul
3. a spirit, i.e. a simple essence, devoid of all or at least all grosser matter, and possessed of the power of knowing, desiring, deciding, and acting
   3.a] a life giving spirit
   3.b] a human soul that has left the body
   3.c] a spirit higher than man but lower than God, i.e. an angel
       3.c.1] used of demons, or evil spirits, who were conceived as inhabiting the bodies of men
       3.c.2] the spiritual nature of Christ, higher than the highest angels and equal to God, the divine nature of Christ
4. the disposition or influence which fills and governs the soul of any one
   4.a]. the efficient source of any power, affection, emotion, desire, etc.
5. a movement of air (a gentle blast)
   5.a] of the wind, hence the wind itself
   5.b] breath of nostrils or mouth
derivation: from (4154)
http://bible1.crosswalk.com/Lexicons/Greek/grk.cgi?number=4151&version=kjv

(4154)
1] to breathe, to blow
   1.a] of the wind
derivation: a root word
http://bible1.crosswalk.com/Lexicons/Greek/grk.cgi?number=4154&version=kjv

Additional information:
The known synonyms of the word "spirit" are the words "mind", "heart" and "strength".

Comments:
The fact, that some corrections have been provided below for some definitions, is not meant to suggest that corrections for any of the other definitions are not needful. Corrections are needful, in some cases. Some of the cases are nevertheless indeterminate. That is, some definitions contain allegations and/or implications which are not now known to be either correct or incorrect. This caution applies to some definitions for other words as well, notably for the word "soul".
1] By means of a rigorous analysis of This Good Riddle (which analysis is not yet shown here), it was determined that the word "soul" means "memory" in contrast to the word "spirit" which means "volition". See also the comment for the word "ghost".
2] The essential testimony in paragraph 015-e shows that the Son of Man, Jesus, is not co-equal with the Holy Ghost.
3] The essential testimony in paragraph 071-b shows that the Holy Ghost is co-equal with the Most High God, that is, the God of Abraham, Isaac, and Jacob, because the Holy Ghost is an exact copy of the Most High God.