In English, name Sandra means – Unheeded prophetess. A diminutive of Casirnir, Cassandra, or Catherine. In Homers The Iliad Cassandras prediction of the fall of Troy was unheeded. Also used as an independent name. Also a feminine of Alexander (defender of man).. Other origins for name Sandra include – English, Greek. Name Sandra is most often used as a girl name or female name.