Knight in shining armor is an idiom that has been in use since the turn of the 20th century. We will examine the meaning of the common idiom knight in shining armor, where it came from, and some examples of its idiomatic usage in sentences.
A knight in shining armor is generally an idealized companion. Traditionally, a knight in shining armor refers to a gallant man who comes to woman’s rescue—he may be rescuing her from physical harm, from a difficult situation, or simply, from loneliness. Sometimes, the phrase knight in shining armor simply refers to someone who performs a heroic deed. The expression knight in shining armor did not come into use until the turn of the 20th century, though it stems from imagery popular in medieval times. During that time, stories of dashing and chivalrous knights performing heroic deeds for damsels in distress were popular. These types of stories still live on in fairy tales and romance novels.
Examples
When she recently got trapped in an elevator, this damsel in distress was rescued by her very own knight in shining armor… a member of the New York City Fire Department. (Newsweek Magazine)
The building melody intensifies as Juliet wonders if Romeo will be her knight in shining armor. (The Ithican)
If he is reading this, I hope our “knight in shining armor” knows how thankful four elderly people are. (Baltimore Sun)