To hike is to walk a long way at a leisurely pace. You might love to hike in the woods on weekends.
When you hike, you walk for pleasure, often in a wooded or hilly area. The trip itself is also a hike, whether you hike the Appalachian Trail or climb a local hill. Another meaning of hike is "to increase," as when the library decides to hike the fees for late books. Hike has been around since the 1800's, when it was spelled hyke, but its origin is uncertain. The "walk vigorously" meaning is older than the "raise or increase" meaning.