Rūḥ (روح) is an Arabic word meaning spirit, and appears to be related to the Hebrew word "Ruach" or "Ruah" (רוּחַ) (See: Ruach#Etymology). It is the third among the six purities or al-Laṭaʾif as-sitta (اللطائف الستة). 
The phrase ruach hakodesh (also transliterated ruaḥ ha-qodesh) is used in the Jewish Scriptures and other writings to refer either to the spirit of inspiration as above, or to the general, indwelling revelation of the Divine Presence among the Jewish people, also known as the Shechinah. Although the term appears frequently in post-biblical writings, in Scripture itself, the term appears only in possessive form as רוּחַ קָדְשְׁךָ ruach kadsh'cha, "Thy holy spirit" (Psalms 51:13), and as רוּחַ קָדְשׁוֹ ruach kadsho, "His holy spirit" (Isaiah 63:10,11). Later writings identify other scriptural instances of the word רוּחַ ruach, "spirit," as indicating ruach hakodesh. 
The English word spirit comes from the Latin spiritus, meaning "breath", but also "spirit, soul, courage, vigor", ultimately from a Proto-Indo-European *(s)peis. It is distinguished from Latin anima, "soul" (which nonetheless also derives from an Indo-European root meaning "to breathe", earliest form *h2enh1- . In Greek, this distinction exists between pneuma (πνεῦμα), "breath, motile air, spirit," and psykhē (ψυχή), "soul" (even though the latter term, ψῡχή = psykhē/psūkhē, is also from an Indo-European root meaning "to breathe": *bhes-, zero grade *bhs- devoicing in proto-Greek to *phs-, resulting in historical-period Greek ps- in psūkhein, "to breathe", whence psūkhē, "spirit", "soul".
The word "spirit" came into Middle English via Old French. The distinction between soul and spirit also developed in the Abrahamic religions: Arabic nafs (نفس) opposite rúħ (روح); Hebrew neshama (נְשָׁמָה nəšâmâh) or nephesh (in Hebrew neshama comes from the root NŠM or "breath") opposite ruach (רוּחַ rûaħ). (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 נֶ֫פֶשׁ (root נפשׁ) and רוּחַ (root רוח), as well as cognate words in various Semitic languages, including Arabic, also preserve meanings involving misc. air phenomena: "breath", "wind", and even "odour".