by far - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Also, far and away. To the greatest degree, by a large margin. For example, She is by far the most experienced member of the cast, or, as Anthony Trollope wrote, “He was far and away the cleverest of his party” (The Duke's Children, 1880). The first term dates from the late 1700s, the variant from the mid-1800s. Also see by half.