Nonlinear

[Tina]

Not denoting, involving, or arranged in a straight line.

[Merna]

to [freak out], to crack under stress or pressure.

[Specialized] vocabulary used by [scientists] and engineers.

[Zipporah Schumaker]

Not simple, not easy to [resolve]. Comes from math: whenever you see the word [linear], [you know its] easy.

This word is not restricted to use in math.

[Mark Zuckerberg]

used to describe a process, series of events, etc. in which one thing does not clearly or directly follow from another: