fi·del·i·ty (fĭ-dĕlĭ-tē, fī-)
n. pl. fi·del·i·ties
a. Faithfulness to obligations, duties, or observances.
b. The condition or behavior of engaging in sex only with one's spouse or only with one's partner in a sexual relationship.
2. Exact correspondence with fact or with a given quality, condition, or event; accuracy: the fidelity of the movie to the book.
3. The degree to which an electronic system accurately reproduces the sound or image of its input signal.
[Middle English fidelite, from Old French, from Latin fidēlitās, from fidēlis, faithful, from fidēs, faith; see bheidh- in the Appendix of Indo-European roots.]
Synonyms: fidelity, allegiance, fealty, loyalty
These nouns denote faithfulness. Fidelity implies the unfailing fulfillment of one's obligations and strict adherence to vows or promises: fidelity to one's spouse; acted in fidelity to religious laws. Allegiance is faithfulness considered as a duty: "I know no South, no North, no East, no West, to which I owe any allegiance" (Henry Clay).
Fealty, once applied to the obligation of a vassal to a feudal lord, now suggests faithfulness that one has pledged to uphold: "[The candidate] pushed his experience as an executive and professed his fealty to Democratic Party principles" (David Corn).
Loyalty implies a steadfast and devoted attachment that is not easily turned aside: loyalty to an oath; loyalty to a lifelong friend.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus