At a low point, in a state of decline or depression. For example, The current recession has put our business at a low ebb. This idiom transfers the low point of a tide to a decline in human affairs. [Mid-1600s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.