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hidebound [hidebound 词源字典]: hidebound: [16] The term hidebound was originally applied to cattle so emaciated that their skin (or hide) was dry and stiff and clung closely to their bones. The idea of being trapped immovably inside one’s skin had led by the early 17th century to the meaning we are most familiar with today: ‘set immovably in one’s opinions, narrow-minded’.
[hidebound etymology, hidebound origin, 英语词源]
fast (adv.): Old English fæste "firmly, securely; strictly;" also, perhaps, "speedily," from Proto-Germanic *fasto (cognates: Old Saxon fasto, Old Frisian feste, Dutch vast, Old High German fasto, German fast "firmly, immovably, strongly, very"), from *fastu- (adj.) "firm, fast" (see fast (adj.)).

The meaning "quickly, swiftly, rapidly" was perhaps in Old English, certainly by c. 1200, probably from or developed under influence of Old Norse fast "firmly, fast." This sense developed, apparently in Scandinavian, from that of "firmly, strongly, vigorously" (to run hard means the same as to run fast; also compare fast asleep, also compare Old Norse drekka fast "to drink hard," telja fast "to give (someone) a severe lesson"). Or perhaps from the notion of a runner who "sticks" close to whatever he is chasing (compare Old Danish fast "much, swiftly, at once, near to, almost," and sense evolution of German fix "fast, fixed; fast, quick, nimble," from Latin fixus). The expression fast by "near, close, beside" also is said to be from Scandinavian. To fast talk someone (v.) is recorded by 1946.
immovable (adj.): late 14c., literal and figurative, from assimilated form of in- (1) "not, opposite of" + movable. Related: Immovably.
irremovable (adj.): 1590s, from ir- "not" + removable. Related: Irremovably; irremovability.
synarthrosis: "An immovably fixed joint between bones connected by fibrous tissue (for example, the sutures of the skull)", Late 16th century: from modern Latin, from Greek sunarthrōsis, from sun- 'together' + arthrōsis 'jointing' (from arthron 'joint').