cipher (n.)
late 14c., "arithmetical symbol for zero," from Old French cifre "nought, zero," Medieval Latin cifra, which, with Spanish and Italian cifra, ultimately is from Arabic sifr "zero," literally "empty, nothing," from safara "to be empty;" a loan-translation of Sanskrit sunya-s "empty." Klein says Modern French chiffre is from Italian cifra.

Sources:

• A Dictionary of Selected Synonyms in the Principal Indo-European Languages, University of Chicago (By: Carl Darling Buck) 1988.
• Etymological Dictionary of Latin and the other Italic Languages (By: Michiel de Vaan) 2008.
• The American Heritage Dictionary of Indo-European Roots (By: Calvert Watkins) 2000.
• Noun Declension in Indo-European (Sindhueuropaia Deklination Nomnes) By: Carlos Quiles.
• Online Etymology Dictionary (By: Douglas Harper)