"The Canterville Ghost" is described as a comico-horror story because it has elements which both amuse and scare the reader.

Beginning with comedy, there are a number of humorous elements in the story. Washington Otis's cleaning of the blood stain with Pinkerton's Stain Removal in Chapter One, for example, and Mrs Otis's offer of a tincture in Chapter Three, are both designed to make the reader laugh. The tricks played on the ghost by the twins are also amusing. They attack him with pea-shooters, for instance, and leave nut-shells on the floor for him to stand on.

On the other hand, there are plenty of scary references in "The Canterville Ghost," too. When the Otis's buy Canterville Chase, for example, Lord Canterville asserts that the house is haunted and relates a frightening tale which explains his reason for selling. His great-aunt, the Dowager Duchess, was frightened "into a fit" after seeing skeleton hands on her shoulders while she was dressing for dinner. Similarly, Lady Canterville found herself unable to sleep at night because of the strange noises emanating from the corridor and the library.

The house's murderous history is another scary element in the story. In 1575, Sir Simon murdered his wife, Eleanore, and this act is immortalized by the blood stain in the library. This example is especially important because it demonstrates how Wilde combines comedy and horror to great effect. While the murder is itself a frightening act, Sir Simon's motivations are so trivial that they become funny to the reader:

My wife was very plain, never had my ruffs properly starched, and knew nothing about cookery.

In sum, then, Wilde is able to make the reader laugh and feel fear and, in some cases, feel both emotions at the same time.

Describe "The Canterville Ghost" as a story.

"The Canterville Ghost" is a short story written by Oscar Wilde. It begins with the Otis family, who are Americans, buying the Canterville mansion in England. The previous owner warns the Otis family that the house has been haunted for many years by a ghost named Sir Simon. The Otis family doesn't believe the story for the simple reason that they do not believe in ghosts. Not long after taking possession of the house, the Otis family is forced to admit that the ghost and the haunting is real; however, the story never becomes a "scary ghost story." In fact, the story becomes a comedy as it parodies the stereotypical ghost story. One reason that the story never becomes truly scary is because the Otis family simply refuses to be scared of the ghost. In fact, the two young Otis twins make it their personal goal to antagonize Sir Simon at every possible moment. It gets to the point that Sir Simon is scared to even leave his hiding places. The only family member that takes pity on Sir Simon is Virginia, and Sir Simon pleads with her to help him finally cross over to his eternal resting place. Virginia agrees to help Sir Simon, and she accompanies him to the Garden of Death where he can finally sleep forever. The story ends with Virginia getting married. Her husband asks her what happened between her and the ghost, and Virginia refuses to tell him.

Describe "The Canterville Ghost" as a story.

"The Canterville Ghost" makes fun of (parodies) the typical ghost story. In the typical story, a frightening ghost haunts an ancestral English hall, terrorizing the people who live there. In this story, Wilde turns that idea on its head: a practical American family terrorizes a ghost. They are not afraid of it at all. When it leaves bloodstains on the library floor, they simply rub the stains out with a new cleaning formula. When the ghost tries to scare them, the young Otis boys shoot at it with a pellet gun and make a water slide so it will slip and fall. 

But beneath the comedy, Wilde has a more serious purpose. He raises our sympathy and compassion for the ghost. The ghost is not simply a "thing" that is out there and must be destroyed, but a human being (albeit one existing between the living and the dead) with emotions and problems. In encouraging the reader not to stereotype an "other," such as a ghost, Wilde calls into question the ways we stereotype people who are not quite like us. 

Why is "The Canterville Ghost" a mix of comedy and horror?

"The Canterville Ghost" is a horror story because parts of the story are genuinely creepy and scary.  In the story, readers are told that Sir Simon brutally murdered his wife and has been haunting the house for generations.  Additionally we learn about a blood stain that can't be removed.  It reappears despite all best efforts to clean it.  Further scares come from the ghost himself.  When he first appears to Mr. Otis, Sir Simon is dragging chains with him and has burning red eyes.  

The story is a comedy because despite Sir Simon's best efforts, the Otis family flat out refuses to be afraid.  It's not just that they put on a brave face either.  They are literally not scared in the slightest.  For example, Mr. Otis is more annoyed with Sir Simon that first night than scared.  That's why Mr. Otis hands the ghost some oil and asks him to kindly keep the noise down.  The twins end up antagonizing the ghost.  They set up trip wires for him, they throw pillows at him, and they even scare the ghost with fake ghosts.  Sir Simon spends most of the story plotting new ways to scare the Otis family only to be defeated in a funny way.