region in northeastern Germany, late 14c., Prusse (late 13c. as a surname), from Medieval Latin Borussi, Prusi, Latinized forms of the native name of the Lithuanian people who lived in the bend of the Baltic before being conquered 12c. and exterminated by (mostly) German crusaders who replaced them as the inhabitants.
Perhaps from Slavic *Po-Rus "(Land) Near the Rusi" (i.e. Russians; compare Pomerania). The German duchy of Prussia after the 17c. union with the Mark of Brandenberg became the core of the Prussian monarchy and later the chief state in the German Empire. The center of power shifted to Berlin after the union, and the old core of the state came to be known as East Prussia.
"work with, practice with persistence, use or employ diligently," late 14c., shortened form of applien "join to, apply" (see apply). The core of this is Latin plicare "to lay, fold, twist," from Proto-Italic *plekt-, from PIE root *plek- "to plait." The sense of "travel regularly, go back and forth over the same course" is attested from 1803, perhaps from earlier sense "steer a course" (1550s). Related: Plied; plies; plying.
Old English mentel "a loose, sleeveless garment worn as an outer covering, falling in straight lines from the shoulders," from Latin mantellum "cloak" (source of Italian mantello, Old High German mantal, German Mantel, Old Norse mötull), perhaps from a Celtic source, or, if the Latin word is the same word as mantelum, mantelium "a cloth, hand-towel, napkin," perhaps it is from manus "hand."
Reinforced and altered 12c. by cognate Old French mantel "cloak, mantle; bedspread, cover" (Modern French manteau), also from the Latin source. Figurative sense "that which enshrouds, something that conceals, a covering" is from c. 1300. Allusive use for "symbol of literary authority or artistic pre-eminence" (by 1789) is from Elijah's mantle (II Kings ii.13). As a layer of the earth between the crust and core (though not originally distinguished from the core) it is attested from 1940. To take (originally have) the mantel (and the ring) was a symbolic act done before a bishop by a widow, indicating a vow of chastity (c. 1400).
"the act of removing (a kernel, seed, tumor, etc.) from its cover or capsule," 1640s, noun of action from verb enucleate (1540s), from Latin enucleatus "pure, clean," past participle of enucleare "to lay open, explain in detail," literally "to remove the kernel from" (see ex- + nucleus). Mostly figurative in Latin (the notion is of getting at the "core" of some matter), and usually figurative in English until mid-19c. advances in science and medicine gave it a new literal sense.