(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.

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.

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

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.

(obsolete) The relationship of a godmother to the other god-parents, and the legal parents, of a child. / In polygamy, a wife of one's father who is not one's mother; that is, co-wife of one's mother.

of a woman, an aunt of one's niece or nephew who is not one's sister; a co-sister-in-law as common aunt to the children of two women's married siblings.

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.

(obsolete) The relationship of a godfather to the other god-parents, and the legal parents, of a child.

simple past tense and past participle of co-locate