How can I install a new language (latin in this case) for my word?

You can create a character style with the "Do not check grammar or spelling" attribute set and apply it to text in Latin.

Do the following (see the screen shot below):

A. In the Styles pane (Ctrl+Alt+Shift+S), click the New Style icon.

B. In the Create New Style... dialog box, type a name for your style, and set the style type to "Character."

C. Click the Format drop down, and then click Language.

D. In the Language dialog box, click to select the "Do not check spelling or grammar" option. Note that you have to specify a language as well for the new style. You can't leave the language choice blank, even though you are turning off spellchecking.

When you are done, apply the character style to the appropriate text ranges in the document.

Google Translate can translate from Latin. I don't know how useful it is.

Microsoft does not offer Latin as a proofing language, if that is what you are asking.

Thanks. Until Latin is added (please Microsoft!) I have just turned off the spelling/grammar check on those documents with a lot of Latin.

Latin is not an available language in Word for Mac, unfortunately, and I too would like to know if there is a way to set a document as "Latin". As to translating, you may wish to try https://latin-words.com/. It does not translate like a true translator, but it does give the lemma and conjugation/declension information for entered words.

Hello Lourdhu,

Thank you for reaching out,

You can use the Office language options to add a language, to choose the UI display language, and to set the authoring and proofing language.

The language options are in the Set the Office Language Preferences section of the Office Options dialog box, which you can access by going to File > Options > Language. The display and authoring languages can be set independently. For example, you could have everything match the language of your operating system, or you could use a combination of languages for your operating system, authoring, and Office UI display.

To add a display language:

1. Open an Office program, such as Word.
2. Select File > Options > Language.
3. Under Office display language, on the Set the Office Language Preferences, select Install additional display languages from Office.com.
4. Choose the desired language in the Add an authoring language dialog and then select Add. A browser page opens where you can download the installation file.
5. On the browser page, select Download and run the downloaded pack to complete installation. 6.The added language appears in the list of Office display languages.

To add an authoring language:

1. Open an Office program, such as Word.
2. Select File >Options >Language.
3. On the Set the Office Language Preferences, under Office authoring languages and proofing, select Add a Language....
4. Choose the desired language in the Add an authoring language dialog and then select Add. A browser page opens where you can download the installation file.
5. On the browser page, select Download and run the downloaded pack to complete installation.
6. The added language appears in the list of Office authoring languages.

see more details;

https://support.microsoft.com/office/663d9d94-ca99-4a0d-973e-7c4a6b8a827d#:~:text=Open%20an%20Office%20program%2C%20such,dialog%20and%20then%20select%20Add.

Warm regards.

Jackson.