Simple past tense and past participle of concertina.(verb)
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Use "concertinaed" in a sentence
""But you used to laugh at him," bugled Dan, fists balled and forehead concertinaed in rectangular outrage."
"And all this, mind, a century before the Montgolfier brothers ever hoisted themselves aloft, so expect your time frames and tenses to be concertinaed as your credulity is stretched to its breaking point."
"The writings comprised cascade upon cascade of dramas small and large concertinaed into a few hundred words; entertaining to read, but it felt like she had harvested a week's worth of incident and excitement and shoe-horned them into a day or less."