Watches evolved from portable spring-driven clocks, which first appeared in 15th century Europe. Watches weren't widely worn in pockets until the 17th century. One account says that the word "watch" came from the Old English word woecce which meant "watchman", because it was used by town watchmen to keep track of their shifts at work.[5] Another says that the term came from 17th century sailors, who used the new mechanisms to time the length of their shipboard watches (duty shifts).[6]