You dab something when you gently pat at it, usually with a cloth. You might dab at your forehead with a handkerchief, or dab on something in blotches. The woman in the picture has dabs of sunscreen on her face.
Dampen is another word for suppress. Acoustic insulation like in the picture will dampen sound. Being given some bad news may dampen your spirits and put you in a bad mood.
Dancing is a way of moving that is usually set to music and is pleasant to watch. There are many different kinds of dance, from very formal dances like ballet that have defined movements, tribal and traditional dances from many cultures, through to unstructured dancing that young people do at nightclubs.
Something dangles if it is hanging loosely, so that is can move around freely. People often dangle toys for kittens so they will play with them.
A debate is a structured discussion about the pros and cons of an issue. Each side of the discussion will either be for or against a point of view and will put forward the reasons for their side of the debate. A similar word to debate is argument.
You demolish something when you take it apart until there is nothing left. When you say demolish, you usually mean a building being demolished.
You destroy something when you damage it so badly it is completely useless. You can destroy something by smashing it into tiny pieces, burning it or by dissolving it.
A detour is a path taken that goes out of the way of your usual path. Detours are usually set up when there is some obstacle and there needs to be a way around it. Used as a verb, it simply means you are taking a detour, for example "I am going to detour past the shops on my way home".