Is it farther or further?
a salt of hydrocyanic acid, 1826, coined from cyan-, comb. form for carbon and nitrogen compounds, from Greek kyanos "dark blue" (see cyan) + chemical ending -ide, on analogy of chloride. So called because it first had been obtained by heating the dye pigment powder known as Prussian blue (see Prussian).
cyanide cy·a·nide (sī'ə-nīd') or cy·a·nid (-nĭd)
Any of various salts or esters of hydrogen cyanide containing a CN group, especially the extremely poisonous compounds potassium cyanide and sodium cyanide.