noun
cooking over a fire from an unclean or mourning household; food prepared over such a fire
A traditional Shinto-related term referring to the act of cooking using fire from a home considered ritually unclean (e.g., due to death or childbirth) and the food thus prepared. Often contrasted with 別火 (separate fire). Rare in modern everyday usage.
See also: 別火
昔は、喪中の家の火で料理することを合い火と呼んで避けた。
In the past, cooking over the fire of a house in mourning was called aibi and was avoided.
合い火の考え方は、別火と対になる伝統的な穢れの観念に基づく。
The concept of aibi is based on the traditional notion of impurity, paired with the idea of bekka (separate fire).
別火 refers to the practice of using a separate, ritually pure fire, while 合い火 refers to using a fire from an unclean source.
Compound of 合い (ai, 'together, joint') and 火 (hi, 'fire'), referring to sharing or using the same fire. The exact historical derivation is uncertain, but it is associated with Shinto purity customs.