(rare) A distant in-law: A relationship by marriage with a separation by three degrees (two people), compared to prototypical in-laws, where the separation is two/one. The separation may be two degrees of blood kin and one of marriage (addressing the mother of the husband of one's daughter), or one degree blood and two of marriage (addressing the brother-in-law of one's brother, or, similarly, addressing the wife of the brother of one's husband).

(uncommon) The mother of one's children-in-law; that is, the mother-in-law of one's children, or, the mother of one spouse in relation to the parents of the other spouse; either of two or more women whose children marry each other, such as the mother of a bride vis-à-vis the mother of the groom.

One's spouse's sister-in-law, especially one's husband's brother's wife, one's brother's wife in relation to the spouses of his siblings; either of two (or more) women who are married to brothers, in relation to the other.

The largest lake in Japan, located in Shiga prefecture.

A parent of one's son- or daughter-in-law, that is, a parent-in-law of one's son or daughter.

plural of co-father-in-law

The father of one's son- or daughter-in-law; that is, the father-in-law of one's child, or, the father of one spouse in relation to the father of the other spouse; either of two or more men whose children marry each other, such as the father of a bride vis-à-vis the father of the groom.

(rare) One's spouse's sibling's spouse; either of two (or more) people who marry siblings, from the perspective of the other.

(uncommon) One's spouse's brother-in-law (one's spouse's sibling's husband), especially one's wife's sister's husband; either of two (or more) men who marry sisters, in relation to the other; the brother of one spouse in relation to the siblings of the other spouse.

An adage which proposes that every act has unintended consequences.