I would define hiking simply as walking on terra firma. A less strenuous or slower amble might be called a wike (walk+hike).
According to Zikkir the origin of hike is as follows:
From English dialectal hyke (“to walk vigorously”), probably a Northern form of hitch, from Middle English hytchen, hichen, icchen (“to move, jerk, stir”). Cognate with Scots hyke (“to move with a jerk”), German dialectal hicken (“to hobble, walk with a limp”), Danish hinke (“to hop”).
When one thinks about other common uses of hike, we come up with a basic pulling upward motion, like: “to hike a football”, “y’all hike them britches,” or “the dreaded price hike of gasoline.” It is even a common command used by mushers to stir their sled dogs into action.
So, fundamentally, we’ve got movement (not always smooth), stirring, and rising. Now, what exactly is moved?
Where I live the topography can be dramatic, and to travel through Nature usually means an elevation gain or loss, as well as an accumulation of mileage. So, in this case the body travels up through the dense forest and up onto the year-round snow patches where the views are expansive, clearing, and inspiring.
Inspire, from the latin inspirare, means to inhale the breath of the spirit. Physiologically, the alveoli of the lungs take in oxygen molecules and transfer them to the blood where they are used for energy production and waste removal; from gas to liquid right there in your chest. Wow, to me that is magic! It is through this deep breath and coursing blood that real healing can occur.
One of my heros, John Muir, whom you will undoubtedly hear more from, said this, “In every walk with Nature one receives far more than he seeks.”