Merriam-Webster's Word of the Day for February 18, 2024 is: fathom \FA-thum\ verb

To fathom something is to understand the reason for its existence or occurrence.

// Even those close to him can't always fathom why he repeatedly risks his life to climb the world’s tallest mountains.

[See the entry >](https://www.merriam-webster.com/dictionary/fathom)

Examples:

"[Oppenheimer](https://www.britannica.com/topic/Oppenheimer-film) provides an opportunity to revisit this charismatic, contradictory man and reconsider how previous attempts to tell his story have succeeded—and failed—at fathoming one of the 20th century’s [most fascinating public figures](https://www.britannica.com/biography/J-Robert-Oppenheimer)." — Andy Kifer, Smithsonian Magazine, 18 July 2023

Did you know?

Fathom comes from the Old English word fæthm, meaning "outstretched arms." The noun fathom, which now commonly refers to a measure (especially of depth) of six feet, was originally used for the distance, fingertip to fingertip, created by stretching one's arms straight out from the sides of the body. In one of its earliest uses, the verb fathom was a synonym of our modern [embrace](https://www.merriam-webster.com/dictionary/embrace): to fathom someone was to encircle the person with your arms. By the 1600s fathom had taken to the seas, with the verb being used to mean "to measure by a [sounding line](https://bit.ly/47uZTT1)." At the same time, the verb also developed senses synonymous with [probe](https://www.merriam-webster.com/dictionary/probe) and [investigate](https://www.merriam-webster.com/dictionary/investigate), and it is now frequently used to refer to the act of getting to the bottom of something, figuratively speaking.