The word 'unsigned' is a straightforward modern English compound formed by the productive application of the native negative prefix 'un-' to the adjective 'signed.' The core concept of 'sign' originates from Latin signum, meaning a mark or token used for identification. In the context of documents, a signature is a personal mark of authentication. Therefore, 'unsigned' literally means "not marked with such a sign." This logic extends seamlessly into computing terminology, where an unsigned integer is one not marked with (i.e., lacking) a sign to indicate positive or negative value, thus defaulting to non-negative.

Structure: un (not) + signed (having a signature) - un: A prefix of Germanic origin (Old English un-), meaning "not." It functions as a negative particle. - signed: The past participle form of the verb 'sign,' from Latin signum (mark, token). It functions as an adjective meaning "having been marked with a signature."