If something is sclerotic, it is becoming hard and not able to change.
Sclerotic can make people think of being stuck, old, or not able to move forward.
Examples:
The sclerotic rules made it hard for new ideas to happen.
The sclerotic system wouldn't let anyone try new things.
The sclerotic government couldn't make any changes.
The sclerotic computer was so old, it could only show black and white pictures.
The sclerotic tree was so hard, even the wind couldn't move it.
The sclerotic old cat wouldn't play with anything new.