Top 5 Most Obscure Words I have Encountered while Reading 'Cloud Atlas'

1. Scrimshandered: adj. carved or engraved of whale bone or whale ivory
• Moreover, he possessed a handsome army of scrimshandered chessman whom we shall keep busy until either the Prophetess's departure or the Nellie's arrival.
2.  Tatterdemalion: adj. ragged, unkempt or dilapidated
• No more tatterdemalion a renegado I ever beheld, but Mr. Evans swore the quadroon, Barnabas, was "the fleetest sheepdog who ever ran upon two legs".
3. Parvenu: n. a person who has recently or suddenly acquired wealth, importance, position, or the like, but has not yet developed the conventionally appropriate manners, dress, surroundings, etc.
•  These parvenu farmers clear the land by bushfires that smolder beneath the peat for many seasons, surfacing in dry spells to sow renewed calamity.
4. Pusillanimity: n. timidity, cowardliness
• These provocations the Moriori faced as our Lord importuned, by "turning the other cheek" and the transgressors returned to New Zealand confirming the Moriori's apparent pusillanimity.
5. Fecundated: v. to make prolific or fruitful, to impregnate or fertilize
•  Chatham Isle encloses a vast eastern salt marsh lagoon, Te Whanga, very nearly an inland sea but fecundated by the ocean at high tide through the lagoons "lips" at Te Awapatiki. 

*All of these words are from the first section of the book: 'The Pacific Journal of Adam Ewing'.  David Mitchell has, very masterfully, written each section of the book in the style of the time it is set in. Since this section is set in the 1850's he has crafted the vocabulary, language and sentence structure accordingly. I could choose many more than five words from each section but these were my favorite.