The yeasty foam that rises to the surface of fermenting malt liquors.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "barm" in a sentence
"A large apron -- which Clarice called a barm-cloth -- protected the dress from stain."
"AlcoholAfter the liquid cools, yeast is added to form barm, which is put into fermentation tanks to convert the sugars into alcohol."
"I am assuming the "hops liquid natural starter" is a "barm", either traditional ale beer barm or simply liquid natural starter with hops added in."