Imagine walking through a wide open park with no one else around. You hear the birds singing, smell the grass and maybe a hint of flowers. It's a warm, sunny day and all is good with the world. Do you think that there's anything likely to hurt you in this situation?
There are no bears, lions or tigers. There's no plane about to fall out of the sky onto your head, there are no local volcanoes, you are magically cured of any hayfever, the sun isn't about to go supernova and any visiting space aliens are far too busy looking for cows to mutilate to take any interest in what's up your bottom.
That's pretty safe, right? You'd feel okay about, say, holding a friend's baby or a kitten or a Fabergé egg.
Now imagine you're not walking on the nice, soft grass but along a plank between two rocks. It's only 6" off the ground but it's also only 6" wide. Don't feel so safe now, do you? Would you carry the egg? Probably. The kitten? Probably. Both would survive a fall onto soft grass. The baby likely would too, but most of you would be less willing to take the chance.
Now imagine that the plank is six feet up and I lied about the lion. It's right there and it's angry and hungry and you need to cross the plank to get over a calm, gently-flowing river and escape. You'd take the baby, rather than let it get eaten, maybe the kitten. Probably not the egg. Lions don't eat Fabergé eggs.
What if the plank is only 4" wide, suspiciously splintered, and twenty feet above a raging torrent inhabited by man-eating fish, mutant crocodiles and evil, poisonous, aquatic monkeys? Would you rather try kicking the lion in the face?
In each of these situations you have assessed a situation of increasing danger and weighed up the options as to which is the preferable course of action.
The dictionary definition of risk is:
n hazard, danger, chance of loss or injury; the degree of probability of loss; a person, thing or factor likely to cause loss or danger...