(adj) not spreading pollution or contamination; especially radioactive contamination, Syn. uncontaminating, Ant. dirty, Example:a clean fuel; cleaner and more efficient engines; the tactical bomb is reasonably clean
(adj) spreading pollution or contamination; especially radioactive contamination, Syn. contaminating, Ant. clean, Example:the air near the foundry was always dirty; a dirty bomb releases enormous amounts of long-lived radioactive fallout