Adjective

1. Roughly-made, unsophisticated, decrepit (from the use of haywire for temporary repairs). Possibly originated because of frayed wires sitting near hay in a hot barn, which caused an explosion (The barn ceased to exist, and it was referred to as having gone "haywire"), or from tendency of slap-dash repairs done with scraps of bailing wire to fail catastrophically at times of mechanical stress.
2. Behaving erratically or uncontrollably, especially of a machine or mechanical process; usually used with the verb "go".
   • It was working fine until it went haywire and wouldn't stop printing blank sheets.
   • Those kids go haywire when they don't get what they want.

Related terms

• come unglued
• tearing up Jack
• lose one's cool
• blow up
• go bonkers