Something that is not strong and might break easily.
The word slimsy makes people think of things that are not good or safe.
Examples:
The slimsy chair broke when I sat on it.
I don't trust this slimsy bridge.
The slimsy rope couldn't hold the heavy box.
I tried to use the slimsy umbrella, but it blew away!
The slimsy paper tore as soon as I touched it.
The slimsy wall fell down in the wind.