Our hero is Sulley, huge and blue and furry, the best scarer in the building. His job is to walk out of a wardrobe at two in the morning and give a sleeping child a fright. To give someone a fright is to startle them suddenly, and a fright is short and sharp — you get one in a second, but you can be afraid for years.

Here is the joke the film is built on. The monsters are terrified of the children. They believe one touch from a human child would kill them. So the scariest creatures in the city are, underneath it, scared stiff — so frightened that you cannot move. Fear locks you in place.

Then a small girl follows Sulley home through a door that should not have been open. He calls her Boo. She is perhaps three years old, and she does not bat an eyelid — she shows no reaction at all to something that would shake anybody else. Boo looks up at eight feet of blue fur, laughs, and calls him Kitty.

Everyone else would jump out of their skin — so startled that your body moves before you have decided anything. It is an exaggeration, and English speakers use it constantly. Mike Wazowski, Sulley’s best friend, a small green monster who is mostly eye and entirely mouth, does it roughly once an hour.

Hiding a child means hiding her from everybody, and the two of them spend the film being spooked by ordinary things — a noise in the corridor, a shadow that moves. To be spooked is to go suddenly uneasy about something you cannot quite see. It is much lighter than terrified.

Mr Waternoose, who runs the company, has a power shortage and a short temper. Children are harder to frighten every year, and his scarers keep losing their nerve on the floor. To lose your nerve is to have the courage and then feel it go, usually at the worst possible moment.

Living with Boo changes what Sulley thinks his job is. He watches her draw and play and fall asleep on his chest, and then he watches a recording of himself at work, and what he sees sends a shiver down his spine. That phrase means a physical, cold feeling, and it works for horror and for beauty both.

What follows asks him to face his fears — to go towards the thing you are most afraid of instead of away from it.

Mike, who is not brave and knows it, has to pluck up the courage to follow him: to gather it a little at a time, because you do not have it naturally.

The words reviewers reach for are the five bonus words above. Critics praised the creative world of doors, scare floors and monster streets, and the scare floor itself is a noisy place, all sirens and machines.