Having a somewhat salty taste, especially from containing a mixture of seawater and fresh water: "You could cut the brackish winds with a knife/Here in Nantucket” ( Robert Lowell).
Distasteful; unpalatable: a thin, brackish gruel.
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.