Synonyms for Ebb:

n.

crater, dip, drop, shrink. channel, recede, burst, approach, retrograde, crest, break, Retrocede, dash, retract, deepen, cast up, retreat, come in, catch. drown, lay down your life, pass away, lose your life, slackening, remission, subsidence, starve, breathe your last (breath), abatement, suffocate, perish, letup, expire. departure (noun)
retreat.
ebb (noun)
ebb off, reflux, ebb away, ebb out, wane, ebbing, ebb down.
event (noun)
reflux.
let-up (noun)
subsidence.
process (noun)
ebbing, wane.
recession (noun)
falling off, regression, reduction, waste, lessening, depreciation, abatement, outward flow, shrinkage, Ebb tide, diminution, withdrawal.
regression; decline (noun)
decay, withdrawal, drop, outward flow, retreat, reflux, slackening, shrinkage, wane, abatement, subsidence, lessening, diminution, depreciation.
slackening (noun)
slackening.

v.

deteriorate (verb)
downgrade, get worse, wane, retrogress, degenerate, tergiversate, regress, decay, putrefy, fall apart, worsen, lapse, revert, slide, collapse, dilapidate, wilt, fade, slump, sink, atrophy, deteriorate, go downhill, relapse, wither, slip, decline, moulder.
motion (verb)
ebb away, ebb down, ebb off, ebb out.
pacify (verb)
pacify, ease, hush, assuage, allay, lull, soften, mollify, placate, moderate, stabilize, relieve, appease, cool, quiet, compose, smooth, soothe, calm, quell, defuse, conciliate, reconcile, tranquilize.
subside; decline (verb)
fall, sink, dwindle, recede, shrink, deteriorate, degenerate, moderate, let up, slacken, Retrocede.

Other synonyms:

fall, bate, peter, slackening, Retrocede, subsidence. eddy, recede, maelstrom, dwindle, letup. die, abatement, rebate, remission, slacken, retrograde. drain, remit. retract. current. drip, flush. course. in. down. decrease
peter, slack off.
die
dilapidate.
peter
tail away.
recede
recede, Retrocede.
waste
waste.

Usage examples for ebb

  1. And, in the glow of starting, he couldn't see that Polly's spirits seemed at a low ebb and he drew a long breath as he tried to make himself believe that what he had noticed at luncheon wasn't really so at all. – Five Little Peppers at School by Margaret Sidney
  2. Somehow, the whole tide of his purpose seemed suddenly to ebb – VC -- A Chronicle of Castle Barfield and of the Crimea by David Christie Murray