Rare historical term for the twelfth month of the lunar calendar, equivalent to 師走 (しわす). Used in classical or poetic contexts.
See also: 師走
In old calendars, the twelfth month was sometimes called 親子月.
The exact derivation is uncertain; the kanji 親子 (parent and child) may reflect a traditional association with family gatherings at year-end, but this is speculative.