Saint
comes from a Greek word meaning,
A sanctified person; a holy or
godly person; one who is physically pure and morally blameless or religious; one who
is set apart unto God.
All believers are
called saints.    
Likewise the Spirit also helpeth our infirmities:
for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered.
And He that searcheth the hearts
knoweth what is the mind of the Spirit,
because He maketh intercession
for the saints according to
the will of God.

Romans 8:
26 and 27
saint 1. A person sanctified;
a holy or godly person; one eminent for piety and virtue.  It
is particularly applied to the apostles and other holy
persons mentioned in Scripture....  
Webster's   
1828