Better AI translations start with a short glossary

AI assistants translate fluently, and that is exactly why their mistakes get through. A clumsy sentence makes a reader stop and check; a smooth sentence with the wrong word sails past. The slips that cause trouble are small ones: your own terms rendered three ways in one document, a date read in the wrong order, a billion that grows a thousandfold, a product name turned into an ordinary Spanish word.

A short glossary prevents most of them, and you build it once. By the end of today you’ll have a glossary of your own terms saved next to a translation prompt that uses it, and one real document translated and checked.

The method suits anyone who works between English and Spanish: HR teams writing to offices in two countries, support agents answering in both languages, project managers with colleagues in Monterrey and Madrid, teachers in bilingual programs. The examples go from English into Spanish; the method works the same in the other direction and between any two languages. For a two-line note to a colleague, a plain request and a careful reread are enough. The glossary pays off on documents many people read and on the ones you translate every month.

Where AI translation slips

• Your own terms. “Leave” comes back as licencia in one paragraph and permiso in the next, and readers assume two words mean two different things.
• False friends. “Actual costs” are costos reales, because actual in Spanish means current. “Eventually” is al final or con el tiempo; the RAE’s Diccionario panhispánico de dudas (DPD) advises against eventualmente in that sense, as a calque of the English word. “Attend a meeting” is asistir a una reunión, since atender means to look after or to pay attention to.
• Large numbers. An English billion is mil millones. A Spanish billón is a million million.
• Decimal marks. Mexico writes 2.5 and Spain writes 2,5 (the RAE lists who uses which). So 12.546, an example from the RAE’s own Ortografía, is over twelve thousand in Madrid and just over twelve and a half in Mexico City. And in Mexico a dollar sign means pesos.
• Dates. 03/04/2027 is March 4 to an American reader and 3 April to most Spanish-speaking readers, who put the day first (DPD, fecha).
• Register. A text that opens with usted can slide into tú halfway down, often in the instructions (“haz clic aquí”).
• Names. Products and programs named with ordinary words get translated. For example, an HR portal called Compass turns into Brújula, and nobody can find it in the menu.

Build the glossary once

Gather two or three documents your team has already written, such as announcements or FAQs. Paste them into a new chat with this prompt:

Below are [two or three] documents my team writes in English.
List the 30 terms that should be translated into Spanish the same
way every time: job titles, team and department names, program and
policy names, recurring phrases, and any word with a specific meaning
in our organization.

For each term give:
term | suggested Spanish | one alternative | why it needs a fixed translation

Then, in a separate list, give every name that should stay in English:
products, systems, programs, people and places.

[PASTE THE DOCUMENTS]

The assistant proposes; you decide. Go down the rows one at a time and keep the translations that match what your Spanish-speaking colleagues already write (a quick search of their emails settles most doubts); fix the others. Stop at 20 to 30 entries: a longer list is harder to keep current, and the terms that matter get lost among the obvious ones.

Name the variety at the top, because the right word changes with the country: paid leave is permiso con goce de sueldo in a Mexican HR office and permiso retribuido in a Spanish one. If you write for both, choose neutral international Spanish and note the local terms.

GLOSSARY: English > Spanish (Mexico). Updated October 15, 2026

term | translation | note
paid leave | permiso con goce de sueldo | Spain office: permiso retribuido
manager | jefe inmediato | the person someone reports to
employees | colaboradores | our internal word
business days | días hábiles |
part-time | medio tiempo | Spain office: a tiempo parcial

DO NOT TRANSLATE
Compass (HR portal), Excel, Teams

Save it as a document with the date in its name. If your assistant can keep files or standing instructions in a project, put it there too; Set up your AI assistant once shows how.

The translation prompt

Paste the glossary with every translation, along with these rules:

Translate the text below from English into Spanish for [Mexico / Spain /
a mixed audience: neutral international Spanish].

Rules:
- Use the glossary for every term it lists, every time.
- Leave the names on the DO NOT TRANSLATE list exactly as written.
- Address the reader as usted throughout. Never switch to tú.
- Dates: day, month in words, year (4 de marzo de 2027).
- Numbers: [decimal point, as in 2.5 / decimal comma, as in 2,5].
  Translate "billion" as "mil millones". Write amounts with the
  currency code (USD, MXN, EUR).
- Watch for false friends such as actual, eventually and attend.
- Keep the meaning, including every condition and every "may".
  Add nothing and leave nothing out.

After the translation, list every place where you were unsure: an
ambiguous term, a word missing from the glossary that you had to choose,
or a sentence you restructured. Quote the English and say what you
chose and why.

GLOSSARY
[PASTE]

TEXT
[PASTE]

Read the list of doubts first: it points to the sentences where the assistant knows it made a choice. Every doubt about a term the glossary didn’t cover is a new row waiting to be written. Add it now, and the next document won’t raise it. The list won’t flag every guess, which is why the next two checks exist.

Check the meaning in a fresh chat

Open a new conversation, so the assistant can’t see your original. Paste the Spanish of the paragraphs that matter most, the ones with dates, amounts, deadlines and who qualifies, and ask:

Translate this into English as literally as you can.
Don't improve the style or fill any gaps.

Put the result next to your original and compare meaning, sentence by sentence. Has a “may” become a “must”? Has a condition, an exception or a date changed or gone missing?

A back-translation is good at one thing: shifts in meaning. It won’t show stiff or unnatural Spanish, and it often misses false friends, because the same mistake reverses neatly, so “eventually” becomes eventualmente and comes back as “eventually”. Anything published or binding, such as a policy or a public web page, still gets a read from a fluent Spanish speaker before it goes out.

Search for every term

Paste the translation into a document and use find (Ctrl+F, or Cmd+F on a Mac). Search for the Spanish of each glossary entry and confirm it appears wherever the English term did. Then search for the usual suspects: actual, eventual, atender, billón, and the tú forms tus, puedes, tienes, debes. For tu itself, type a space after it, or the search will stop inside every actual and estructura. Each hit gets a look; many will be fine.

A worked example

For example, a made-up company with offices in Chicago and Guadalajara announces a new leave policy. One paragraph of the English:

Starting 03/01/2027, employees can take up to 2.5 days of paid leave per quarter for family matters. Request them in Compass at least five business days ahead. Your manager will reply within two business days. Eventually, we plan to extend the policy to part-time staff.

Without a glossary, these are the slips to look for: the date read as January 3, Compass translated, paid leave worded differently from your other HR documents, “your manager” as tu gerente, and “Eventually” as Eventualmente, which suggests to a Spanish reader something that may or may not happen. With the glossary and the rules above, the checked version reads:

A partir del 1 de marzo de 2027, los colaboradores podrán tomar hasta 2.5 días de permiso con goce de sueldo por trimestre para asuntos familiares. Solicítelos en Compass con al menos cinco días hábiles de anticipación. Su jefe inmediato le responderá en un plazo de dos días hábiles. Más adelante, planeamos extender esta política a los colaboradores de medio tiempo.

Each fix traces back to a line in the glossary or the prompt, and the search for eventual confirms the last one, which a back-translation would have missed.

Try it today

1. Run the glossary prompt on two or three documents your team has already written, and decide every row. Give it 20 to 30 minutes.
2. Save the glossary with the date in its name, and paste the translation prompt at the top of the same document.
3. Pick one real document you need in Spanish this week, ideally one many people will read, such as an announcement or a web page. If it holds anything confidential, read Before you upload a client document first.
4. Translate it with the prompt, read the list of doubts and add any new terms to the glossary. Then back-translate the key paragraphs in a fresh chat and run the searches.
5. Write down how long the whole thing took. Time the next document too, now that the glossary exists, and compare.

You’re done when the glossary is saved and the checked translation sits next to its original.

Where to go next

A translation is only as clear as its original: a sentence with three conditions keeps all three in Spanish. So the next step is to fix the source. Rewrite a dense document in plain language walks you through it; translate the plain version with your glossary afterward and see whether the list of doubts gets shorter. Keep the glossary and the prompt with the rest of your best prompts, and if you answer the same emails in both languages, build your templates from the sent folder in pairs.