slate
noun
°A fine-grained homogeneous sedimentary rock composed of clay or volcanic ash which has been metamorphosed so that it cleaves easily into thin layers.
°The bluish-grey colour of most slate.
adjective
°Having the bluish-grey/gray colour/color of slate.
verb
°To cover with slate.
°(chiefly British) To criticise harshly.
synonyms: slate grey, slate gray, account, bill