(n) a ductile grey metallic element of the lanthanide series; used in lighter flints; the most abundant of the rare-earth group, Syn. Ce, atomic number 58
(n) a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal, Syn. Cs, caesium, atomic number 55
(n) a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks), Syn. I, atomic number 53, iodin
(n) a white soft metallic element that tarnishes readily; occurs in rare earth minerals and is usually classified as a rare earth, Syn. atomic number 57, La
(n) a soft yellowish-white trivalent metallic element of the rare earth group; can be recovered from bastnasite or monazite by an ion-exchange process, Syn. Pr, atomic number 59
(n) a brittle silver-white metalloid element that is related to selenium and sulfur; it is used in alloys and as a semiconductor; occurs mainly as tellurides in ores of copper and nickel and silver and gold, Syn. Te, atomic number 52
(n) a silvery malleable metallic element that resists corrosion; used in many alloys and to coat other metals to prevent corrosion; obtained chiefly from cassiterite where it occurs as tin oxide, Syn. atomic number 50, Sn