unofficial era name; apocryphal era name
A rare historical term for a Japanese era name (年号) that was proposed or used unofficially, outside the officially recognized list. Often contrasted with 逸年号 (いつねんごう), which refers to era names omitted from official histories.
See also: 逸年号
An 'inen-gō' refers to an unofficial era name not recorded in the official histories.
Compound of 異 (i, 'different; unusual') and 年号 (nengō, 'era name'). The exact historical derivation is uncertain; the term is used in Japanese historiography to describe non-standard era names.