The definitions with perpetrators identified by asterisks and voters in parentheses

A) one of the last mammals to be discovered by science (1900). It lives in the dense rainforests of Zaire and little is known of its behavior. themilum*

B) a coarse tightly-woven fabric, produced in the coldest northernmost parts of Great Britain. wofahulicodoc* (TEd Remington)

C) a midden or gut-pile. Elizabeth Creith* (Father Steve)

D) (obs.) a Visigoth pestle used to grind mortar. AnnaStrophic*

E) Cheap and inferior imitative products of Chinese manufacture. From English sailors' mispronunciation of the Chinese manufacturing city of Wu-Tsin (modern Changzhou). Father Steve* (Aramis11)

F) a steel alloy having a pattern of bands or sheets of micro carbides within a tempered martensite or pearlite matrix. Also known as Indian steel or Damascus steel, thought to have gained its strength from carbon nanotubes. From One Look with amplification from Nature Science Update. (wofahulicodoc, ParkinT, tsuwm)

G) n. [Colloq.] debris observed in flowing liquid; flotsam Aramis11* (musick, Elizabeth Creith)

H) Several pleasant discoveries, arriving at the recipient in a stream faster than can be processed, from the plural of "woot", a popular cultural exclamation of delight. ParkinT*

I) onomatopoetic Dutch word for a stone for sharpening skate blades, from the characteristic sound it makes as it is drawn across the blade. TEd Remington* (etaoin, AnnaStrophic)

J) (eponym, after Jean Wootz who was executed during the Reign of Terror) someone devoted to humanitarian ideals and to the liberal ideas of the Encyclopédie. tsuwm* (Alex Williams)

K) The original name for the cheerleaders from the University of Minnesota. The cheer "wootz" came after Charles "the hammer" Wootz broke the collegiate sack record in 1907 with 14 sacks in one game against rival Princeton. musick* (themilum)

Wofa, ParkinT and tsuwm got it correct. Aramis11 suckered in musick and Elizabeth Creith. TEd got etaoin and the lovely AnnaS.