What ruach means
Ruach sits at the intersection of three realities that Hebrew never separates the way we do: breath, wind, and spirit. The word names something you cannot hold but cannot live without. In its most physical register, ruach is the air moving in and out of your lungs, the wind bending the grass on a hillside, the breath of God that animated the first man's nostrils. But Hebrew thought did not fence off the physical from the spiritual, and ruach carries that wholeness with it everywhere it appears.
When the ruach of God moves over the face of the deep in Genesis 1:2, you are meant to feel both the wind and the Spirit at once, not choose between them. When Elijah runs to the wilderness and lies down exhausted, it is the ruach of God that eventually sends him back to the work. The word names whatever animating force makes the difference between a body that moves and a body that does not, between a nation with courage and a people broken by fear.
Ruach also describes human emotion and inner disposition. Proverbs speaks of a broken ruach as the deepest kind of wound, deeper than a broken body. Numbers describes Caleb as having a different ruach, a different spirit inside him, which is what made him willing to trust God when ten others would not. The word stretches from meteorology to theology without losing its breath, which is itself the point. God's presence is never inert. Wherever ruach appears, something is moving.
Etymology
Ruach comes from a root meaning to blow or breathe, sharing its basic shape with the verb ruach used rarely but pointedly in Scripture for the act of breathing and smelling. Its cognates appear across Semitic languages: Arabic ruh carries the same breath-spirit range. Related Hebrew forms include the noun form used for the four winds and the verb form describing relief or spaciousness, giving ruach a semantic family that spans direction, breath, freedom, and life-force.