The origin of the phrase to take umbrage is troubling Mary Kelleher, a lady from Kinsale, Co Cork. Her dictionary, like most, confuses as much as it helps, by stating that umbrage is from Middle English, borrowed from Middle French, ultimately from Latin umbra, shade or shadow. No great help, says Mary, and I agree with her.
Umbrage first came into English in the 15th century. It then meant shadow or shade. This meaning was known to Milton, who, in 1667, wrote in Paradise Lost that the "highest woods, impenetrable to star or sunlight, spread their umbrage broad, and brown as evening". But at the very beginning of the 17th century another sense had been given the word: a shadowy suggestion of something. You'll remember Shakespeare in Hamlet speaking of "His semblable [likeness] in his mirror, and who else would trace him, his umbrage, nothing more". This sense was borrowed directly from a secondary meaning of the Latin umbra, the shade or ghost of a dead person. In that same 17th century umbrage took on yet another, sinister, sense, a shadow of a suspicion thrown on somebody. From there it's but a short hop to the modern sense, displeasure or offence.
Tim Murphy, from Raheny, Dublin, wrote to ask about the origin of the word bunk, used by Henry Ford to define history. The word is a shortened from of bunkum, and this word should really be spelled Buncombe, which is a county in North Carolina, and home of a Congressman named Felix Walker. In 1820, Felix delivered a famously longwinded speech on the Missouri Question to the 16th Congress. It was so long and so fatuous that he had to put up with heckling even from his own party members. Afterwards he defended himself by saying that he made his speech "for Buncombe", just to remind his electors he was doing his bit for them up in Washington. Sounds familiar?
Buncombe quickly became a synonym for a leadranach bit of political guff. From this it's not a long semantic jump to any kind of insincere speechifying. The word was spelled buncombe in America until about the turn of the century. As such, Mark Twain has it in Pudd'nhead Wilson in 1894: "He said that he believed that the reward offered . . . was humbug and buncombe." In time the word came to be spelled bunkum, and around 1900 it was shortened to bunk.