Meaning

verb convert code into ordinary language

verb read with difficulty

originAs decypher, but not retaining the y from the Old French etyma of cipher (cyfre, cyffre); the i spelling tends to be preferred etymologically, being consistent with its cognates, the French déchiffrer and the Italian decifrare, and with their common ancestor, the Medieval Latin cifra, cifera, ciphra. By surface analysis, de- + cipher.

Etymology from Wiktionary, CC BY-SA 3.0