'slate-like' is formed from the English noun 'slate' and the adjectival suffix '-like'. 'slate' originates from Old English 'slǣte', where 'slǣte' meant 'a flat stone (used for roofing)', and the suffix '-like' originates from Old English 'lic', meaning 'having the form or appearance of'.

'slǣte' (Old English) developed into Middle English 'slate' and then modern English 'slate'. The Old English adjective-forming element 'lic' evolved through Middle English into the modern suffix '-like', which attaches to nouns to form adjectives (e.g. 'slate-like').

Initially, 'slate' referred specifically to the flat roofing stone and '-lic' meant 'having the nature or form of'; combined, 'slate-like' historically described something similar to slate and has retained the basic meaning 'resembling slate' in modern usage.