Have you seen tweets with people talking about their "SO?" That's probably not the word "so" accidentally typed in all-caps. It's a totally different term.

Significant Other

SO stands for "significant other." People on the internet use it to refer to their spouse or partner. For example, someone might say, "I asked my SO if she wanted to get lunch."

It's often used to provide a very neutral way of referring to a partner without disclosing or implying any specific details about them. By using SO, you don't reveal their name, gender, or the stage of the relationship you're currently at. Your SO can be a boyfriend or girlfriend, or they can be someone you've been married to for years.

SO is always typed in uppercase letters to distinguish it from the word "so." Sometimes, it includes periods between the letters, such as "S.O.," to clarify that it's an acronym. It's also spoken in real-life contexts sometimes, so you may hear some people saying, "I'm meeting with my S.O." when you ask them where they're headed.

The Origin of SO

The phrase "significant other" has been around for a very long time. Its first use dates back to an article by American psychiatrist Harry Stack Sullivan, who explored the dynamics of interpersonal relationships.

It later started being used online on early internet message boards and instant messaging apps. Its first definition on Urban Dictionary dates all the way back to November of 2001 and reads, "abbreviation for Significant Other."

It eventually rose to popularity thanks to chat apps like iMessage and WhatsApp, and social media, especially Twitter. Because of Twitter's character limits, "SO" became a common way to refer to someone's partner. At just two characters, it's much shorter than words like "husband" or "spouse" and continues to be widely recognizable.

What Is "Significant?"

Most people use SO as a catch-all, neutral term for anyone you're in a relationship with. For example, when you're inviting your friends to a game night over Zoom, you might include in the invite, "Bring your SO!" That means that you're okay with them bringing someone they're partnered with, whether they're dating, partnered, or married.

When someone uses SO to refer to their own partner, they're normally referring to someone they're in a long-term relationship with. This is true even if the acronym deliberately obfuscates those kinds of details. That is why you're most likely to see it used by people in married, engaged, or highly committed relationships instead of people in short-term relationships. Ultimately, what counts as "significant" may vary significantly depending on the relationship two people have.

An alternate use of SO is in formal contexts, such as filling out an emergency contact form. These forms may use "significant other" as a catch-all, instead of asking for a spouse name, as a way of including other types of long-term relationships.

Similar Slang Terms

Along with "SO," there are other slang terms used by people to refer to a partner or someone you're currently in a committed relationship with.

Significant Other has some similarities to a less-common internet slang term, "DH" or "dear husband." DH rose to popularity in the mid-2000s in internet boards where women talked about marriage, motherhood, and family life. It can either be used in a sarcastic manner or to soften the blow of stories where they would complain about their husband. It was often accompanied by the slang terms "DD" and "DS," which stood for "dear daughter" and "dear son," respectively.

Other acronyms used by people in long-term relationships include "FH" and "FW," which stand for "future husband" and "future wife," respectively. They are used by people when talking about the person they're engaged to be married to. Another is "FI," which is an abbreviated form of fiancee. These slang terms are most commonly seen in message boards, social media groups, and forums related to wedding planning.

How to Use SO

If you want to use SO, swap it out when discussing someone you're in a relationship with. For example, if you don't want people to know you're engaged, where you might say "my fiance," you can say "my SO." Make sure that it's in all-caps as well. Otherwise, people will think it's "so."

Here are a few examples of SO in action:

• "My SO got a dog yesterday!"
• "I'm going to fly out tomorrow morning and meet up with my SO at Indianapolis."
• "What kind of birthday gift should I give my SO if he's into baseball?"

We hope that you learned an easy, short way to refer to your partner! If you want to learn some other internet acronyms, check out our articles on OTOH, FWIW, and DW.

Related: What Does "FWIW" Mean, and How Do You Use It?