What is the primary meaning of "fathom" as a verb?

The primary meaning of "fathom" as a verb pertains to understanding something deeply. This usage stems from its origin related to nautical terminology, where a "fathom" was a measurement of depth in water, typically six feet. However, over time, the word evolved to symbolize the act of comprehending complex ideas or emotions thoroughly.

When someone says they are trying to "fathom" a situation, they imply they are making an effort to grasp its full significance or to delve into its complexities. This depth of understanding is what makes the term particularly rich and meaningful in various contexts, such as literature or discussions about human behavior.

In contrast, the other choices focus on measurement or navigation, which do not capture the essence of deep comprehension that defines the correct answer. Therefore, the emphasis on understanding illustrates why it is the most accurate representation of "fathom" in its verbal form.