The first name Sandra is of Greek, English origin. It is often a girl name. It has the following meaning(s):
Greek: Helper of Humanity
Greek: Helper of Mankind (From Alexandra)
English: Unheeded Prophetess. A Diminutive of Casirnir, Cassandra, or Catherine. in Homer's 'The Iliad' Cassandra's Prediction of the Fall of Troy Was Unheeded. Also Used As an Independent Name. Also a Feminin
Greek: Variant of Alexandra: a Feminine Form of Alexander Meaning Defender of Men, Used in Britain Since Early Th Century; it Became Popular After the Marriage of Future King Edward Vii to Princess Alexandra