Trekking is one of the most popular outdoor activities for more than 1 day where travelers enjoy nature, mountains, lifestyles, culture, tradition, and festivals far from home. Trekking is the most popular activity in Nepal because of the higher mountains including Mount Everest. TREKKING definition: 1. the activity of walking long distances on foot for pleasure: 2. the activity of walking long…. Learn more. The meaning of TREK is to make one's way arduously; broadly : journey. How to use trek in a sentence. The meaning of TREK is to make one's way arduously; broadly : journey. How to use trek in a sentence.