The crossword solution for the term 'HUMAN'S TAIL' is 'OID', which is an acronym for 'obsolete, inactive, and discarded'. This term is used to describe items that are no longer in use or have been discarded. It is commonly used in the context of computer programming, where it refers to software or hardware components that are no longer needed or used. In the context of humans, it can refer to a TAIL that has been lost or removed.