Pompadour

Madame Pompadour without a pompadour hairstyle, 1758)

The pompadour is a hairstyle. Not many people get a hairstyle named after them. In modern times, I can only think of the "Rachel" named for the Rachel Green character on TV's Friends and played by Jennifer Aniston. 

Back in the 18th century, Madame de Pompadour was a mistress to King Louis XV and his political advisor. The hairstyle is named for her, But the name for this hairstyle has nothing in common with the hairstyle of Madame de Pompadour. She wore her hair back rather than up, and without the extra volume on the top. The name for the hairstyle wasn't coined until after her time.

In the 1890s, the Gibson Girl look used the style. The 1925 novel, The Great Gatsby, references Jay Gatsby as having had a pompadour in his youth. It came back in vogue for women again in the 1940s.

Betty Grable 1942     Link

The men's version appeared in the 1950s and early 1960s, worn by early country, rock and roll and movie stars such as Elvis Presley, Judy Garland, Johnny Cash, Chuck Berry, Ritchie Valens, James Dean, and Tony Curtis. 

Elvis  1954   Link

It had a revival in the 2000s with celebrities including John Travolta in Grease, Justin Timberlake, David Beckham, Rihanna, Bruno Mars and others.

Silhouette

18th-century silhouette portrait

A silhouette is the image of a person, animal, object, or scene represented as a solid shape of a single color, usually black, with its edges matching the outline of the subject. The interior of a silhouette is featureless, and the silhouette is usually presented on a light background, usually white, or none at all. 

The word silhouette is derived from the name of Étienne de Silhouette, a French finance minister. In 1759, he was forced by France's credit crisis to impose severe economic demands upon the French people, particularly the wealthy. His austere economies caused his name to be attached with anything done or made cheaply.

These outline portraits were popular prior to the advent of photography. They were cut from black cards and were the cheapest way of recording a person's appearance. 

Apparently,  Étienne de Silhouette enjoyed making such drawings and used them to decorate his chateau.

Modern silhouette of Johannesburg skyline - CC BY-SA 4.0, Link

Decibel

A decibel (dB) is a unit of measurement that came from the need to describe the efficiency of telephone circuits. It would replace "transmission units" which were from the telegraph days. It was decided that they wanted to use a name that connected to the inventor of the telephone, Alexander Graham Bell and created the unit of a "bel." The bel is seldom used, as the decibel was the proposed working unit.  "Deci" denote one-tenth of the "bel" measurement. The new measurement was proposed in 1924 by the Bell Telephone Laboratories. 

In a non-technical sense, most people just think of a decibel as a way to measure the loudness of a sound. Breathing is 10 decibels; conversations in a restaurant is about 60; a motorcycle at 25 ft is 90 dB; live rock music is about 108 - 114 dB.

Bell at the opening of the long-distance line from New York to Chicago, 1892 Link