noun.a pack that usually has two shoulder straps and is carried on the back: such as

• The logistics of the trip required that I carry all my stuff in a backpack. Since I didn't want to lug too heavy a load on the hiking leg of the trip, I pared way down.
• I rode my bicycle to the market and rode home with my backpack full of exotic lettuces and basil-garlic baguettes.

noun.a large pack (as of canvas or nylon) that is supported by an external or internal frame (as of aluminum) and is used especially for carrying supplies when hiking and camping

• Each morning, tens of thousands of moms load phones, along with homework, into the backpacks of schoolchildren.
• By wearing a jet-propelled "space backpack," astronauts will be able to move freely in space, making it possible to build, repair, and maintain craft in orbit …

noun.a bag or small pack (as of canvas, polyester, or nylon) used for carrying personal belongings or supplies: knapsack

• I'm soaring above the central Sahara in a powered paraglider, a single-seat aircraft that looks like a flying lawn chair. Developed in France, it combines an inflated, parachute-like wing with a 50-pound motorized backpack.

verb.to carry (food or equipment) on the back especially in hiking

• We had to backpack everything to last the week.

verb.to hike with a backpack