Haversack
/ˈhævərsæk/
Definition 1 of 1
Pro Tip 1/3Single Strap
A haversack is identified by one strap, unlike backpacks, which have two. 
He slung the haversack over his left shoulder as he left.
Pro Tip 2/3Outdoor Activities
Haversacks are often used for outdoor adventures like hiking or camping. 
She grabbed her haversack before starting the nature trail.
Pro Tip 3/3Versatile Use
Although associated with the outdoors, haversacks can be used in urban settings too. 
He used his haversack to carry his books to the coffee shop.