What is the meaning of cracker?

noun

• A thin crisp wafer made of flour and water with or without leavening and shortening; unsweetened or semisweet.
• A poor White person in the southern United States.
  • synonyms: redneck
• A programmer who cracks (gains unauthorized access to) computers, typically to do malicious things.
  • usage: "crackers are often mistakenly called hackers"
• Firework consisting of a small explosive charge and fuse in a heavy paper casing.
  • synonyms: firecracker, banger
• A party favor consisting of a paper roll (usually containing candy or a small favor) that pops when pulled at both ends.
  • synonyms: snapper, cracker bonbon