Cardboard material suitable for making posters.(noun)
A piece of such material.(noun)
A flyer printed on stiff cardboard, approximately 8.5 by 11 inches, mailed flat.(noun)
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Use "posterboard" in a sentence
"I had no idea – beyond the most rudimentary, high-school sex-ed posterboard kind of understanding – what might be the implications of circumcising or not circumcising."
"Artist Eric Daigh, 33 year old husband, father born in California and now residing in Northern Michigan, creates portraits by putting ordinary pushpins in posterboard."
"One man held a posterboard saying, "you a traitor sic.""