From a (as a negative particle) and zume; unleavened, i.e. (figuratively) uncorrupted; (in the neutral plural) specially (by implication) the Passover week -- unleavened (bread).
KJV: Now the first day of the feast of unleavened bread the disciples came to Jesus, saying unto him, Where wilt thou that we prepare for thee to eat the passover?
NASB: Now on the first day of Unleavened Bread the disciples came to Jesus and asked, "Where do You want us to prepare for You to eat the Passover?"
KJV: After two days was the feast of the passover, and of unleavened bread: and the chief priests and the scribes sought how they might take him by craft, and put him to death.
NASB: Now the Passover and Unleavened Bread were two days away; and the chief priests and the scribes were seeking how to seize Him by stealth and kill Him;
KJV: And the first day of unleavened bread, when they killed the passover, his disciples said unto him, Where wilt thou that we go and prepare that thou mayest eat the passover?
NASB: On the first day of Unleavened Bread, when the Passover lamb was being sacrificed, His disciples said to Him, "Where do You want us to go and prepare for You to eat the Passover?"