Fidelity Meaning: Faithful to People, Promises and the Original

The fidelity meaning in two senses

1. Loyalty and faithfulness. Keeping your commitment to someone or something. Most often this is sexual and emotional faithfulness between partners, but it also covers loyalty to a friend, a country, a principle or an employer.
2. Accuracy. How exactly something reproduces, follows or matches a source. Engineers speak of the fidelity of a signal, translators of fidelity to the original text, and researchers of fidelity to a study plan.

Both senses share one idea: staying true. In the first you stay true to a person; in the second a copy stays true to its original.

Fidelity definition with everyday examples

• After twenty years together, they still treat fidelity as the base of their marriage.
• Her fidelity to the team never wavered, even when a rival company offered her more money.
• The new speakers play old vinyl records with surprising fidelity.
• Critics praised the film adaptation for its fidelity to the novel's ending.
• The nurse checked the trial's fidelity by making sure every patient got the same dose at the same time.

Fidelity through the centuries

English borrowed fidelity several centuries ago from French fidélité, from Latin fidelitas. The Latin root fides means faith or trust, the same root behind confide, confident and bona fide.

The audio sense grew in the twentieth century. Engineers called recordings that copied sound well high fidelity, and the short form hi-fi came to mean home sound equipment.

How to use fidelity in a sentence

Fidelity is a noun, normally used without a plural. Common patterns are:

• fidelity to something: fidelity to the truth, fidelity to the original design
• marital fidelity or sexual fidelity for faithfulness between partners
• high fidelity and low fidelity for quality of copying; designers say lo-fi for rough sketches and hi-fi for polished mockups
• with great fidelity: the map shows the coastline with great fidelity

To describe a person, you would usually use the adjective faithful or loyal rather than turning fidelity into an adjective.

Fidelity, loyalty and faithfulness compared

Loyalty is the broader word. Fidelity sounds more serious and is the natural choice when the topic is marriage or exact reproduction. Its opposite in relationships is infidelity.

Mistakes learners make

Some readers think fidelity only means sexual faithfulness. That is the most common sense, but a headline about "fidelity to the constitution" is about loyalty to a legal text, not romance.

Another slip is spelling: it is fid-el-ity, with one d and one l. Also avoid "fidelity towards"; English prefers fidelity to. Finally, many companies use the word in their names, so a sentence about "fidelity" in a finance context might be a brand rather than the plain word. Check the capital letter and context.

Where you will meet this word

In relationships and counselling, fidelity describes the trust between partners and the promise of monogamy. In religion, it can describe faithfulness to God or to vows. In law and insurance, a fidelity bond protects a business against losses caused by dishonest employees. In technology and design, people compare high fidelity and low fidelity prototypes. In research, treatment fidelity means a program was delivered the way it was planned.

The idea connects closely to integrity: in each case the question is whether something stays whole and true. Plenty of similar words wait in our everyday vocabulary list.