Unmotivated

He usually pretends to be an unmotivated English teacher, but he's actually a CIA agent.

I guess I'm just unmotivated.

I was super unmotivated today.

The presentation in Rudin is not only terse, but also dry and unmotivated.

Near-synonym: demotivated

an unmotivated student

When a typically chatty employee who often participates in meetings and is engaged and enthusiastic suddenly becomes unmotivated and quieter, that person could be at risk for burnout.

Near-synonym: unprovoked

an unmotivated murder

An inherited etymology should not involve too many unmotivated irrregular sound changes aor ^([sic]) non-trivial semantic shifts.