The twitching would disappear for a time for no fathomable reason, and reappear again.
They are fathomable; for carried to a certain pitch of intensity they end in ecstasy or they end in death.
But in every other sense, in all that touches the fathomable business of daylight, she has been a conspicuous success.
They are fathomable; for even in the souls of "the immortals" they are only instruments of life warring against death.
Old English fæðm "length of the outstretched arm" (a measure of about six feet), also "arms, grasp," and, figuratively "power," from Proto-Germanic *fathmaz "embrace" (cf. Old Norse faðmr "embrace, bosom," Old Saxon fathmos "the outstretched arms," Dutch vadem "a measure of six feet"), from PIE *pot(e)-mo-, from root *pete- "to spread, stretch out" (see pace (n.)). There are apparent cognates in Old Frisian fethem, German faden "thread," which OED explains by reference to "spreading out."
Old English fæðmian "to embrace, surround, envelop;" see fathom (n.). The meaning "take soundings" is from c.1600; its figurative sense of "get to the bottom of, understand" is 1620s. Related: Fathomed; fathoming.
(Old A.S. faethm, "bosom," or the outstretched arms), a span of six feet (Acts 27:28). Gr. orguia (from orego, "I stretch"), the distance between the extremities of both arms fully stretched out.