英语词源字典 - 在线词源网站

caked (adj.)[caked 词源字典]: "thickly encrusted," 1922, past participle adjective from cake (v.).[caked etymology, caked origin, 英语词源]
encrust (v.): also incrust, 1640s, from French incruster, from Latin incrustare "to cover with crust," from in- (see in- (2)) + crusta (see crust). Related: Encrusted; encrusting.
saltpeter (n.): "potassium nitrate," c. 1500, earlier salpetre (early 14c.), from Old French salpetre, from Medieval Latin sal petrae "salt of rock," from Latin sal "salt" (see salt (n.)) + petra "rock, stone" (see petrous). So called because it looks like salt encrusted on rock.