"Unsigned contracts" refers to legal agreements or documents that have not been signed by the parties involved. It means that the terms and conditions laid out in the contract are not officially agreed upon or legally binding. Full definition
Validity of unsigned contracts for the sale of land, Statute of Frauds. (johnosullivanlaw.com)
In general, courts will only accept unsigned contracts in special circumstances that it is unquestionable that both parties knew and agreed to the terms and that the terms were reasonable. (law.stackexchange.com)
You might be thinking of web «click through» contracts as examples of unsigned contracts, but such things are highly limited in what they can enforce, and in practice, there are many ways to challenge such contracts, especially if they have any kind of unusual clause. (law.stackexchange.com)