Something is damp if it is slightly wet. The rocks around the waterfall are damp, and moss is growing on them.
Something is dangerous if it is likely to hurt you in some way. Crossing the bridge in the photo is dangerous because it is very narrow and it is likely you will fall into the water.
Large wild animals are dangerous because they are unpredictable and may attack you.
Danish describes anything relating to Denmark, people from Denmark, the language spoken in Denmark and a kind of pastry.
It is dark when there is not much light and you have trouble seeing anything. It gets dark at night time, or when you close the curtains and shut the light out. The opposite of dark is light or bright.
Dark may also be used to describe something that has much deeper colors than something else, or is close to black. The opposite of this kind of dark is pale.
Someone is deaf if they cannot hear things properly, or they cannot hear things at all. People who are only partially deaf can use a hearing aid to help them hear things properly again.
A plant is deciduous if it loses its leaves each year in the cooler months. Deciduous trees leaves turn from green to shades of orange in autumn, and then fall off. The leaves grow back again in spring.
Something is decorative if it is there for decoration.
Water is called deep if you cannot touch the bottom with your feet when you stand in it. Deep water can be found in the sea, or at the diving end of a pool. Wells and mines are very deep but don't always have water in them.
The man in the picture is diving in some very deep water.
Something is delicate if it has fine detail, or is fragile. A color or flavor is delicate if there is only the barest hint of it.
Something is delicious if it smells or tastes really, really good. People would describe something as delicious if they really enjoyed eating it.
And also ...
Dainty, Dank, Dappled, Dear, Deft, Desolate, Devilish, Devoid, Disappointed, Distinct, Divine, Dizzy, Doubtful, Dour, Drunk, Dummy, Dynamic.