fathom

• vt.見抜く；徹底的に理解する；...の深さを測る。
• n. 英寻（水深を測る長さの単位）

PIE*のpet（広げる、伸ばす）が語源で、feather（羽）と語源は同じ。 長さの単位fathomは、大人の両手を広げた長さにほぼ等しい。fathomの語源は「徹底的に知る」。

fathom

fathom: [OE] The underlying etymological meaning of fathom appears to be ‘stretching out, spreading’. It probably comes ultimately from the Indo-European base *pot-, *pet-, which also produced Latin patēre ‘be open’ (source of English patent) and Greek pétalos ‘outspread’ (source of English petal). Its Germanic descendant was *fath-, which produced the noun *fathmaz, direct ancestor of Old English f?thm.

Here, the notion of ‘stretching out’ seems to have spread via ‘stretching out the arms’ to, on the one hand ‘embrace’ (and one meaning of Old English f?thm was ‘embrace, bosom’), and on the other ‘length spanned by outstretched arms’ – about six feet.
=> patent, petal

fathom (n.)

Old English f?em "length of the outstretched arm" (a measure of about six feet), also "arms, grasp, embrace," and, figuratively "power," from Proto-Germanic *fathmaz "embrace" (cognates: Old Norse faemr "embrace, bosom," Old Saxon fathmos "the outstretched arms," Dutch vadem "a measure of six feet"), from PIE *pot(?)-mo-, from root *pet?- "to spread, stretch out" (see pace (n.)). It has apparent cognates in Old Frisian fethem, German faden "thread," which OED explains by reference to "spreading out." As a unit of measure, in an early gloss it appears for Latin passus, which was about 5 feet.

fathom (v.)

Old English f?emian "to embrace, surround, envelop," from a Proto-Germanic verb derived from the source of fathom (n.); cognates: Old High German fademon, Old Norse fatma. The meaning "take soundings" is from c. 1600; its figurative sense of "get to the bottom of, penetrate with the mind, understand" is from 1620s. Related: Fathomed; fathoming.

1. I really couldn 't fathom what Steiner was talking about.

スタンナが何を言っているのか分からない。

2.We 're trying to fathom out what 's going on.

私たちは何が起こっているのかを明らかにしようと努力しています。

3.It is hard to fathom the pain felt at the death of a child.

子を失う痛みは味わえない。

4.I can not fathom his meaning.

私は彼の意味を完全に理解することができません.

5.I 'm having difficulty using my video editing equipment and can 't fathom out the various connections.

私はビデオ編集装置を使用することはできません。そして、さまざまな接続がわかりません。