Prolonged means going on for longer than usual. Prolonged exposure, a prolonged silence, prolonged illness.
It is the word for duration that has become a problem, which is why it appears constantly in safety warnings: prolonged exposure to anything is where the harm starts. A prolonged silence is one that has become awkward.
1adjectiveprolongedGoing on for longer than usual.
“After a prolonged illness, he finally returned to work in the spring.”
prolonged is a quality.