Rb uncommon informal noun 1. a soft silvery metallic element of the alkali metal group; burns in air and reacts violently in water; occurs in carnallite and lepidolite and pollucite Synonymsrubidiumatomic number 37 Related words Broader terms metallic element Parts carnallitelepidolitepollucite WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
