Saki's short story Dusk signifies that dusk is the hour of the defeated in a couple different ways.
First, Norman Gortsby (the protagonist) of the story states very blatantly the fact that only those who are defeated come out at dusk:
Dusk, to his mind, was the hour of the defeated. Men and women, who had fought and lost, who hid their fallen fortunes and dead hopes as far as possible from the scrutiny of the curious, came forth in this hour of gloaming, when their shabby clothes and bowed shoulders and unhappy eyes might pass unnoticed, or, at any rate, unrecognised.
Indirectly, by Norman being out at dusk, Norman is being characterized as being defeated. By the end of the text, Norman is defeated by the young man through the fact that the young man is able to swindle Norman out of money. As hard as Norman tried to prove that the young man was insincere, in the end, the young man is able to get what he wants out of Norman. This fact defeats Norman.
Another example of how the story proves that dusk is the hour of the defeated is the story of the old man. The old man (seen at the end of the text) loses the soap he had bought. The soap represents both the success and the failure of the three main characters in the story. For both Norman and the old man, the soap represents loss. Only for the young man does the soap represent success.
Therefore, in the end, Norman (the one character who seems to have his life together) is the one who comes to be the most defeated in the story. By the end of the story, Norman is not seen as being the only person who is not defeated and out at dusk. Instead, Norman becomes the one most defeated.
The title of Saki's short story "Dusk" can be justified in that criminals usually do their work in darkness or near darkness as in "Dusk." Criminals are rarely seen doing criminal activity in the daylight. They want to protect their identities; therefore, they come out at dark.
In this short story, Gortsby is correct in that people who are defeated or dejected often show up at dusk. They too are protecting their identities. Many are ashamed of their failures and do not desire to be recognized.
Dusk is a perfect time to meander about without fear of recognition. All people have to come out at some point. It makes sense that those who fear being recognized for their failures would prefer to come out when it is nearly dark. Since most people have to come out sooner or later, waiting until it is nearly dark helps conceal their identities. No one will hassle them about their defeats or failures. Hopefully, no one will recognize them.
Saki wrote about the criminal attitudes and behaviors of man. He clearly understood human behavior. He realized that criminals or those who are just defeated would tend to protect themselves from others:
Many of his brilliantly crafted, deeply sarcastic pieces, however, deal with the criminal impulse of man.
At dusk, people appear as shadows. One shadow turns into another shadow. No doubt, the short story's title is justified. Near dark is a perfect time to come out without recognition.