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risk [risk 词源字典]: risk: [17] The ultimate origins of risk have never been satisfactorily explained. English acquired it via French risque from Italian risco, a derivative of the verb riscare ‘run into danger’, but there speculation takes over. One persistent theory is that its ancestral meaning is ‘sail dangerously close to rocks’, and attempts have been made to link it with Greek rhīza ‘cliff’ and Latin resegāre ‘cut off short’ (from the notion of coastal rocks being ‘cut off sharply’ or ‘sheer’). English acquired the French past participial form risqué in the 19th century.
[risk etymology, risk origin, 英语词源]
beetle (v.): "project, overhang," c. 1600, back-formation from bitelbrouwed "grim-browed, sullen" (mid-14c.), from bitel "sharp-edged, sharp" (c. 1200), probably a compound from Old English *bitol "biting, sharp," related to bite, + brow, which in Middle English meant "eyebrow," not "forehead." Meaning "to overhang dangerously" (of cliffs, etc.) is from c. 1600. Related: Beetled; beetling.
dangerous (adj.): early 13c., "difficult, arrogant, severe" (the opposite of affable), from Anglo-French dangerous, Old French dangeros (12c., Modern French dangereux), from danger (see danger).

In Chaucer, it means "hard to please, reluctant to give;" sense of "full of danger, risky" is from late 15c. Other words used in this sense included dangersome (1560s), dangerful (1540s). Related: Dangerously.