What is a clearsigned message?
From dictionary.university with search clearsigned definition


Dictionary of Internet Terms A digitally signed S/MIME or PGP message in which the content of the message is readable even if the signature is not.




A message that is digitally signed but not encrypted.


These might be helpful, too;

Cleartext  is readable data transmitted or stored “in the clear” (i.e. unencrypted)

Plaintext is the input to an encryption algorithm

Ciphertext is the unreadable output of an encryption algorithm

Plain text means its text that hasn’t been formatted (i.e., a plain text file)
Note that plain text might be an ambiguous term without context. See the commnets.