Slate  —n. 1 (esp. Bluish-grey) metamorphic rock easily split into flat smooth plates. 2 piece of this as a tile or hist. For writing on. 3 bluish-grey colour of slate. 4 list of nominees for office etc. —v. (-ting) 1 roof with slates. 2 colloq. Criticize severely. 3 us make arrangements for (an event etc.). 4 us nominate for office etc. —adj.