"nine pieces of knotted cord fastened to a handle and used to flog the bare back," 1690s, probably so called in reference to its "claws." It was a legal instrument of punishment in British Navy until 1881.
"tough outer membrane surrounding the brain and the spinal cord," c. 1400, from Medieval Latin dura mater cerebri, literally "hard mother of the brain," a loan-translation of Arabic umm al-dimagh as-safiqa, literally "thick mother of the brain." "In Arabic, the words 'father,' 'mother,' and 'son' are often used to denote relationships between things" [Klein].
ancient constellation, 12th sign of the zodiac, representing two fishes united by a cord attached to their tails, late Old English, from Latin pisces, plural of piscis "a fish" (from PIE root *pisk- "a fish"). Applied to persons born under this sign by 1924 (also Piscean).