it means that you can see through it. if you take a clear glass plate and put it to your face, you can still see yourself.
Because that object does not reflect light. So glass is transparent because light passes through it. Skin is transparent under X-rays because the skin cannot reflect the high energy Xrays.
Mostly yes, it might be on second thought.
nope
Yes, in the liquid state. In the solid & gas state it is translucent.
Yes it is