Simple past tense and past participle of relapse.(verb)
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Use "relapsed" in a sentence
"These clocks must have been a little before the right time, for it was not till they had again relapsed into silence that there rang out from the ante-room the clear sweet tones, eight times repeated, of "Cuckoo.""
"Often and anxiously the Cabalist shot a glance at his companion, and then again relapsed into reverie."
"If the princes of Britain relapsed into barbarism, while the cities studiously preserved the laws and manners of Rome, the whole island must have been gradually divided by the distinction of two national parties; again broken into a thousand subdivisions of war and faction, by the various provocations of interest and resentment."