the.com/careless
Either you don't care or you forgot to — same word, opposite souls.
means Doing something without the attention or caution it needed, often causing avoidable mistakes.
from From Old English carleas, literally care-less: free of sorrow. The original sense was joyfully untroubled, not negligent — worry-free slid into thought-free over centuries.
Lost twinOnce meant carefree, before it meant sloppy.
Suffix splitThe -less means without, not slightly.
Hidden careSame root powers careful, its exact opposite.