生成单词定义 - 基于给定的单词，生成它的定义和用法例句: "游牧 (nomad)"

游牧
游牧是指一群人通常在较短的周期内，随着季节变化或寻找更好的生计机会而频繁地迁移的生活方式。例如：“在古代草原上，许多蒙古人是游牧民族。”

Nomad refers to a group of people who often migrate frequently with the change of seasons or seeking better opportunities for livelihood in a relatively short cycle of time. For example: "On the ancient grassland, many Mongolians were nomads."