"The Master of the Crabs" by Clark Ashton Smith

inspissation: the act of thickening, or more technically: the process of increasing the viscosity of a fluid, or even of causing it to solidify, typically by dehydration or otherwise reducing its content of solvents.

decoction: the liquor resulting from concentrating the essence of a substance by heating or boiling (typically a medicinal preparation made from a plant)

athanor: a type of furnace used by alchemists, able to maintain a steady heat for long periods

arthame: knife used in casting spells. Apparently this is an older spelling no longer in common use? Today this would be called an 'athame'. It is not entirely obvious to me what the pronunciation should be for this older 'arthame' version.

shagreen: sharkskin used as a decorative material or, for its natural rough surface of pointed scales, as an abrasive. Historically used in some socities for sword grips!

moiety: half

arrack: an alcoholic liquor typically distilled from the sap of the coconut palm or from rice

xebec: a Mediterranean sailing ship of the 16th through 19th centuries, commonly used by the Barbary corsairs

felucca: another type of sailing vessel of the Mediterranean, these more commonly used in the eastern end, especially by the Egyptians

lateen: a triangular sail on a long yard at an angle of 45° to the mast

beefwood: Typically this word is used to describe any of sveral types of Australian tree which have timer of a red color resembling raw beef, although some other trees in South America share the name. Either way, it appears to be a southern hemisphere thing.

riffle: disturb the surface of; ruffle

to ship: in this context: take oars from the oarlocks and lay them inside a boat

thwart: a structural crosspiece sometimes forming a seat for a rower in a boat

breeks: Scottish for breeches

plover: a type of wading bird, of the family Charadriidae

lazuli: short for lapis lazuli, a bright blue metamorphic rock consisting largely of lazurite

chatoyant: a cat's eye gemstone

peroration: the concluding part of a speech, typically intended to inspire enthusiasm in the audience

imprecation: a spoken curse

lubber: a big, clumsy person

The picture used is an illustration by Lee Brown Coye for the story as published in Weird Tales

To follow along: http://www.eldritchdark.com/writings/short-stories/128/the-master-of-the-crabs

Well, well, the villain was made to monologue! We all know how that ends! :)