recede, go out, retreat, flow back, draw back, fall back, fall away, abate, subside;
rare retrocede.
▷antonyms come in.
2 his courage began to ebb:
diminish, dwindle, wane, fade away, melt away, peter out, decline, die away, die down, die out, flag, let up, lessen, decrease, weaken, dissolve, disappear, come to an end;