Complete and total annihilation of a given area and most all that exists there. For the source and more detailed information concerning this subject, click on the related links section (Wikipedia) indicated below.
A release of energy through the fusion of hydrogen isotopes into helium, accompanied by the emission of neutrons. So far on earth this has only been produced for brief periods and has consumed more energy than is produced.
The possible release of nuclear wastes remain a problem.
What were the effects
This is best explained in Glasstones's book The Effects of Nuclear Weapons.
skin cancer
blast effects
Misuses would I think mean nuclear weapons. Harmful effects can be caused by radioactivity if released from the nuclear core, but these are carefully controlled by design and operation to be so low as to not increase local exposure to higher than natural levels.
Poisonous air to breath.
Carnage
Fission and fusion
Radioactive fallout
The blast effects (which is all the question as worded asks about) would be the same as the blast effects of a weight of TNT identical to the nuclear bomb's yield (by definition). However a nuclear bomb has additional effects that the TNT doesn't, but as this question only asked about blast effects, I won't visit them.
Nuclear has radiation. But when used correctly there are no dangerous effects if you are using the proper precautions.
This is best explained in Glasstones's book The Effects of Nuclear Weapons.
mutants
no
Some of the effects on the human body from a nuclear explosion are death (from thermal energy/blast effects or super lethal radiation exposure), infertility and blood disorders.
Blast
unconditional surrender.
skin cancer