What is the meaning of crackers?

noun

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

adjective

• Informal or slang terms for mentally irregular.
  • usage: "it used to drive my husband balmy"
  • synonyms: balmy, barmy, bats, batty, bonkers, buggy, cracked, daft, dotty, fruity, haywire, kooky, kookie, loco, loony, loopy, nuts, nutty, round the bend, around the bend, wacky, whacky