WordNet sense 1 (New Zealand runner who in 1975 became the first person to run a mile in less that 3 minutes and 50 seconds (born in 1952)):

John Walker

WordNet sense 2 (United States writer (born in 1944)):

Alice Malsenior Walker, Alice Walker

WordNet sense 3 (a person who travels by foot):

pedestrian, footer

WordNet sense 4 (a light enclosing framework (trade name Zimmer) with rubber castors or wheels and handles; helps invalids or the handicapped or the aged to walk):

Zimmer, Zimmer frame

WordNet sense 5 (an enclosing framework on casters or wheels; helps babies learn to walk):

go-cart, baby-walker