Diaper
Sometimes adults who do not have medical problems also wear diapers.  This can be for different reasons.  Sometimes it is because they have a profession where they cannot always get to a bathroom, like astronauts. Some adults wear diapers for fun. This is usually a form of sexual pleasure, or for emotional reasons.  These people are often called "diaper-lovers" or "adult-babies." The scientific term for liking to wear diapers is "Diaper Fetishists."