What are the Meanings of Brother-in-law?

Even Latin we have to leave in order to find the etymological origin of the term brother -in-law that now concerns us. Specifically, it comes from the word “cognatus”, which is the result of the sum of two components: the prefix “co-“, which can be translated as “with”, and the word “gnatus”, which is equivalent to “born”..

Brother -in-law is the spouse’s brother or the brother’s spouse. It is a family bond that a person acquires from the marriage of her brother or sister, or if this same person marries and his partner has siblings.

The brother of the spouse and the spouse of the brother is called the brother-in-law.

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Examples of brothers in law

For example: Carlos and Marta are brothers. Silvia is the wife of Carlos and Vicente, the husband of Marta. This means that Carlos and Vicente are brothers-in-law, just like Marta and Silvia.

On the other hand, Silvia ( Carlos ‘s wife ) has a brother named Raúl. Carlos and Raúl, therefore, will also be brothers-in-law. In this way it can be said that Carlos has two brothers-in-law: Vicente (the husband of his sister Deél Marta ) and Raúl (the brother of his wife Deél Silvia ).

The brothers-in-law do not maintain a blood relationship, but the bond arises by affinity (legal bond).

Kinship by affinity

This allows us to affirm that the brother-in-law is a form of kinship that arises by affinity. There is no blood tie that unites the brothers-in-law, but this kinship is created from the union in marriage of a blood relative. Brother-in-law kinship implies a legal bond and not the existence of a natural reason or blood. For legal purposes, brothers-in-law are second-degree relatives with a preferred collateral line of kinship.

The brother-in-law who in Spain, for example, has been very topical in recent years is Iñaki Urdangarín, the brother-in-law of King Felipe VI. And it is that he, who is married to the Infanta Cristina, is accused of a series of money laundering crimes that has caused the monarchy to falter and to be attacked by the population. Hence, the monarch, among other things, has decided to remove him from all official acts.

However, we cannot ignore either that in some countries of the world it is common for brother-in-law to be used with another meaning. Specifically, that term is used to address friends in a loving and affectionate way.

Brother-in-law as company and as surname

It should not be forgotten either that there is a Spanish company called Grupo Cuñado. In the 1960s, it began its activity, which is specialized in the manufacture of all types of tubes or valves, for example, which are used in industries of various kinds.

Likewise, it should not be forgotten that there is an artist whose last name is the word in question. We are referring to Carlos Cuñado, a young artist who stands out for his multidisciplinary character, since he practices various arts such as painting or photography.


The notion of brother -in-law, on the other hand, is used to name someone’s partner with respect to the spouse of another person’s sister. In other words, the partner of a person’s brother-in-law is his sister-in-law.

If we return to our example, Vicente ( Marta ‘s husband, Carlos ‘s sister ) and Silvia ( Carlos ‘s wife ) are brothers-in-law.