Definition of "fathom" in English

noun

1. (chiefly nautical, historical, US) A man's armspan, generally reckoned to be six feet (about 1.8 metres). Later used to measure the depth of water, but now generally replaced by the metre outside American usage.

2. (nautical, US) A measure of distance to shore: the nearest point to shore at which the water depth is the value quoted.

   • After we'd rowed for an hour, we found ourselves stranded ten fathoms from shore.

3. An unspecified depth.

4. Depth of insight; mental reach or scope.

5. The act of stretching out one's arms away from the sides of the torso so that they make a straight line perpendicular to the body.

6. Someone or something that is embraced.

7. Control, grasp.

verb

1. To measure the depth of (water); to take a sounding of; to sound.

2. To encircle (someone or something) with outstretched arms; specifically, to measure the circumference or (rare) length of something.

3. Often followed by out: to deeply understand (someone or something); to get to the bottom of.

   • I can’t for the life of me fathom what this means.

4. To embrace (someone or something).

5. To measure a depth; to sound.

6. To conduct an examination or inquiry; to investigate.