The term 'PETERS OUT' is an idiom which means to gradually become weaker or less active. The crossword solutions EBBS (4 letters), DIES (4 letters), WANES (5 letters), and ENDS (4 letters) all refer to this concept. EBBS is a verb meaning to recede, like the tide ebbing away from the shore. DIES is a verb meaning to cease to exist or come to an end. WANES is a verb meaning to decrease in intensity or strength. ENDS is a verb meaning to come to a stop or conclusion. All of these words are related to the idiom 'PETERS OUT, ' which describes a gradual decrease in activity or strength.