You're standing at a family barbecue. Your brother just married a woman from Mexico City, or maybe your husband’s sister from Madrid is visiting for the holidays. You want to be polite. You want to be accurate. But when you try to figure out how to say sister in law in spanish, your brain hits a wall because Spanish doesn't always play by the same rules as English.
It’s cuñada.
That’s the short answer. If you just need the word for a quick introduction, there it is. Say it like koo-NYAH-dah. But honestly, language is rarely just a one-word exchange. Depending on who you’re talking to, where they’re from, and how formal the vibe is, that one word can shift.
The Core Term: Cuñada and Its Roots
The word comes from the Latin cognata, which basically means "related by birth." Kind of ironic since a sister-in-law is exactly the opposite—someone related by law, not blood.
In Spanish, gender is everything. If you are talking about a brother-in-law, it’s cuñado. If it’s a woman, you use the "a" ending. Pretty standard stuff if you’ve spent more than five minutes on Duolingo. But here’s where people get tripped up: the plural. If you have two sisters-in-law, they are cuñadas. If you have a sister-in-law and a brother-in-law, the group collectively becomes cuñados.
Spanish is a "masculine-leaning" language when it comes to groups. One guy in a room of fifty women makes the whole group masculine. It’s annoying to some, but it’s the linguistic reality you’ll navigate.
Why "Cuñadismo" is a Thing You Should Know
Spanish isn't just a set of labels. It’s a culture.
There is this funny, slightly derogatory term in Spain called cuñadismo. You won't find this in a basic translation guide. It refers to that specific "brother-in-law" energy—you know the one. It’s the person who thinks they know everything about everything, from how to fix a car to the best way to cook a steak, despite having zero actual expertise.
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Even though the root is masculine (cuñado), the concept of the "know-it-all relative" is so baked into the culture that it’s worth knowing. If you call someone a cuñada with a certain roll of the eyes, you aren't just describing a family tie. You’re making a personality commentary.
Regional Slang and Variations
Most of the time, cuñada is the gold standard. You can use it in Bogotá, Buenos Aires, or Barcelona and everyone will know exactly what you mean. But humans are weird, and we love nicknames.
In some parts of Mexico, you might hear people shorten it to cuñis. It’s cutesy. It’s what you’d use in a text message with a heart emoji. It’s the equivalent of saying "sis" instead of "sister."
Then you have the "concunada" situation.
This is where English speakers usually get a headache. In English, if my brother marries a woman, she is my sister-in-law. If my wife has a sister, she is also my sister-in-law. We use one bucket for everyone. Spanish is more surgical.
A concua or concuñada specifically refers to the relationship between two people who are married to siblings.
Example: Your husband has a brother. That brother has a wife. To you, she is technically your concuñada.
You don't have to use it. Most people just stick to cuñada because it’s easier. But if you want to sound like a local who truly understands the intricacies of Hispanic family trees, dropping concuñada at dinner will earn you some serious respect.
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Formal vs. Informal Settings
Does the setting matter? Sorta.
In a legal document or a very formal wedding invitation, you might see "hermana política."
- Hermana = Sister
- Política = Political/By law
It sounds cold. It sounds like you’re talking about a tax bracket. I wouldn't recommend using it in conversation unless you’re trying to be intentionally distant or you’re filling out immigration paperwork. Stick to cuñada.
Pronunciation Secrets for Native Sounds
If you want to sound human and not like a robot, you have to nail the ñ.
The tilde (the little wavy line) isn't just a decoration. It changes the "n" into a "ny" sound, like the middle of the word "canyon."
- Wrong: koon-ah-dah
- Right: koo-nyah-dah
Also, watch the "d." In English, our "d" sounds are hard. We hit them with the tip of our tongue against the roof of our mouth. In Spanish, the "d" between two vowels—like in cuñada—is much softer. It almost sounds like a very soft "th" (like in "the").
Try saying koo-nyah-thah. It feels weird at first, but it’s the difference between sounding like a tourist and sounding like family.
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The Social Nuance of the Word
In many Latin American cultures, family terms are used more loosely than in the US or UK. It’s not uncommon to hear someone call a very close female friend cuñada if they are joking about the friend marrying their brother.
It’s a bit of a tease.
"¡Hola, cuñadita!"
Adding that -ita on the end makes it "little sister-in-law." It’s an affectionate diminutive. It conveys warmth. If you get along famously with your sister-in-law, call her cuñadita. It signals that she’s more than just a legal relative; she’s someone you actually like.
Common Mistakes to Avoid
Don't use sister-en-ley. I know it sounds like a joke, but "Spanglish" can be a slippery slope.
Another big one: confusing suegra with cuñada.
- Suegra is your mother-in-law.
- Cuñada is your sister-in-law.
Mixing those up at a family dinner can lead to some very awkward silences, or at the very least, a very confused mother-in-law who wonders why you think she’s your brother’s wife.
Actionable Steps for Your Next Conversation
If you’re preparing to meet your Spanish-speaking sister-in-law for the first time, don't overthink it. Language is about connection, not perfection.
- Start with the basics. Use cuñada for the introduction.
- Listen for her lead. If she calls you cuñis, feel free to use it back.
- Use the diminutive. If the vibe is warm, cuñadita is a great way to build a bridge.
- Mind the "D." Remember that soft, almost-th sound to keep your accent sounding natural.
- Context matters. If you're talking about her to someone else, use mi cuñada. If you're addressing her directly in a casual way, just cuñada works fine as a nickname.
The most important thing to remember is that in Spanish-speaking cultures, acknowledging the family connection is a sign of respect. By using the specific term rather than just her name, you're acknowledging her place in the family "tribe." It’s a small linguistic gesture that carries a lot of emotional weight.