Definitions of Lao:

noun: the Tai language of a Buddhist people living in the area of the Mekong River in Thailand and Laos
noun: a member of a Buddhist people inhabiting the area of the Mekong River in Laos and Thailand and speaking the Lao language; related to the Thais
adjective: of or relating to a member of the Buddhist people inhabiting the Mekong river in Laos and Thailand
name: A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #9010)