colleague ("sister" in the same craft, occupation, or society) / (India) One's spouse's sibling's wife.

(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).

plural of co-grandparent

(rare) A co-in-law: A relationship by marriage with a separation by three degrees (two people), compared to prototypical affines, where the separation is two and one.

To act as a co-parent; to share custody of a child or children; to share in the responsibility of parenting a child or children.

A godparent. / A divorced or separated parent who shares custody with the other parent. / A parent in a same-sex couple.

of a man, an uncle of one's niece or nephew who is not one's brother; a co-brother-in-law as common uncle to the children of two men's married siblings.

In a polyandrous marriage, another husband of a man’s wife.

the father of one's son- or daughter-in-law, as common grandfather of their children; the relationship between men who have grandchildren in common; maternal grandfather vis-à-vis paternal grandfather.

the mother of one's son- or daughter-in-law, as common grandmother of their children; the relationship between women who have grandchildren in common; maternal grandmother vis-à-vis paternal grandmother.