بسم الله الرحمن الرحيم
In the name of God the Merciful

Every word روح i.e. ‘spirit’ , mentioned in the Quran, means Gabriel, like His saying – be exalted – in the Quran 19: 17
فَأرْسَلْنا إلَيْها رُوحَنا فَتَمَثَّلَ لَها بَشَراً سَوِيّاً
The explanation:
( And We sent to her1 Our ‘spirit’2, who assumed for her the likeness of a well-made man.)
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[1 Mary, mother of Jesus Christ. 2 Gabriel.]

The interpretation: We sent Gabriel, to her; and he appeared before her in the shape of a man.

Moreover, God - be exalted - said in the Quran 2: 87
وَآتَيْنا عِيسَى بْنَ مَرْيَمَ البَيِّناتِ وَأيّدْناهُ بِرُوحِ القُدُسِ
The explanation:
(And We gave Jesus the son of Mary the manifest [miracles] and aided him with the Holy Spirit.)

The ‘Holy Spirit’ or the ‘Holy Ghost’ means Gabriel.

And God - be exalted - said in the Quran 40: 15
يُلْقِي الرُّوحَ مِنْ أمْرِهِ عَلَى مَنْ يَشاءُ مِنْ عِبادِهِ لِيُنْذِرَ يَوْمَ التّلاقِ
The explanation:
(He casts [Gabriel:] the ‘Ghost’ [who is one] of His ‘am`r’ [: ‘spiritual creatures’] upon whom of His slaves [God] pleases [to be an apostle], that he [: the apostle] may warn [people] of the day of meeting [of the past and the later peoples.] )

In addition, God - be exalted - said in the Quran 16: 2
يُنَزِّلُ المَلائكَةَ بِالرُّوحِ مِنْ أمْرِهِ عَلَى مَنْ يَشاءُ مِنْ عِبادِهِ أنْ أنْذِرُوا أنّهُ لا إله إلاّ أنا فَاتّقُونِ
The explanation:
(He [:God] sends down the angels [under the leadership] of the Spirit of His ‘am`r’ to whom He will of His servants, [saying]: Warn [people] that there is no god but I, so ward off My [punishment.] )

The interpretation: He makes the angels to come down [from heaven] by the leadership of Gabriel, upon the one who likes to be an apostle, in order to warn people to abandon the worship of idols and the idolatry.

The Quranic revelations are so many, but we have mentioned some of them as an indication that the word روح i.e. 'spirit' mentioned in the Quran means Gabriel only.

The original Subject be found in this link
http://quran-ayat.com/man/index.htm#The_Spirit_