Okay so the opposite of thixotrophy is rheopecty but apparently oobleck is not rheopectic. In stead it is dilatant. And the opposite of dilatant is pseudoplastic.
So it goes:

• Thixotrophic (time-dependent shear thinning; ketchup)
• Pseudoplastic (non-time-dependent shear thinning; molten polymers and ketchup?)
• Rheopectic (time-dependent shear thickening; gypsum paste)
• Dilatant (non-time-dependent shear thickening; oobleck)

I am a bit confused. Ketchup is thixotrophic as well as pseudoplastic but oobleck is dilatant but not rheopectic. Can anyone give me some intuition on this?

Wiki links:
Pseudoplasticity
Rheopecty
Dilatant