:nonlinear: adj. [scientific computation] 1. Behaving in an erratic
and unpredictable fashion; unstable. When used to describe the
behavior of a machine or program, it suggests that said machine or
program is being forced to run far outside of design
specifications. This behavior may be induced by unreasonable
inputs, or may be triggered when a more mundane bug sends the
computation far off from its expected course. 2. When describing
the behavior of a person, suggests a tantrum or a {flame}.
"When you talk to Bob, don't mention the drug problem or he'll go
nonlinear for hours." In this context, `go nonlinear' connotes
`blow up out of proportion' (proportion connotes linearity).
-- The AI Hackers Dictionary