Birthday of Martin Luther King, Jr.noun [ C usually singular ]
uk/ˌbɜːθ.deɪ əv ˌmɑː.tɪn ˌluː.θə ˌkɪŋ ˈdʒuː.ni.ər/us/ˌbɝːθ.deɪ əv ˌmɑːr.t̬ən ˌluː.θɚ ˌkɪŋ ˈdʒuː.ni.ɚ/a US holiday on the third Monday in January, when people remember the civil rights leader, Martin Luther King, Jr.