letter security letter scales • letter sorter · · · Info · Definitions · Characters · · letter security · · Text Common · · Latin · · Scripts 15 · · Length 6 · · Syllables Definitions · · · (noun) a stock or bond that is not registered with the Securities and Exchange Commission and cannot be sold in the public market. Synonyms: letter security. · · Noun Definition 1 Characters · · space U+0020 c latin small letter c U+0063 e latin small letter e U+0065 i latin small letter i U+0069 l latin small letter l U+006C r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074 u latin small letter u U+0075 y latin small letter y U+0079