SI abbr. 1. super intelligence (US federal usage, 2026) 2. Système international (units) 3. sí (Spanish)
What does SI stand for?
In the context of AI, SI stands for "super intelligence". It's the name the US federal government has used for artificial intelligence since September 2026.
SI = Super Intelligence. It is not "synthetic intelligence" or "superior intelligence". It refers to the same technology people call AI.
Where the name came from
On 19 September 2026 President Trump asked his followers on Truth Social to pick a new name for AI from three options: Superior Intelligence, Extreme Intelligence and Supreme Intelligence. "Super intelligence" wasn't one of them. A second poll, super intelligence against superior intelligence, drew about 50,000 votes, and super intelligence won with about 65%.
On 22 September, at the UN General Assembly, the President said US government documents would use the new term. The executive order followed on 29 September.
Super intelligence or superintelligence?
The order writes it as two words, "Super Intelligence", shortened to SI. Researchers usually write "superintelligence" as one word, and mean something much bigger: a system that outperforms humans at almost everything. You'll see both spellings in the news. In US government documents, two words is the official form.
Other things SI means
If you searched for "what does SI mean" and landed here by mistake, you probably wanted one of these:
| Context | SI means |
|---|---|
| Science and measurement | The International System of Units (metres, kilograms, seconds) |
| Spanish and Italian | "Yes" (sí in Spanish, sì in Italian) |
| Cars | A sporty trim level, best known on the Honda Civic |
| Medicine | Several abbreviations, depending on the specialty |
| Chemistry | Silicon (Si) |
Does it matter which one you use?
If you write for the US federal government, follow its guidance. Everyone else can choose. Most readers still understand "AI" far better, which is why our sister site argues you should just call it AI.