When your spelling is checked, misspelled words are underlined in red, and suggested corrections are shown.

1.On your Mac, choose Apple menu > System Preferences, click Keyboard, then click Text.

2.Select the “Correct spelling automatically” tickbox.

3.In an app, type your content.

4. As misspelled words are detected, do one of the following:

• Accept suggestions: If there’s only one suggestion, just keep typing to have the word autocorrected. If two or more suggestions are shown, choose one.

• Ignore suggestions: Press the Escape key, then continue typing.

• Undo autocorrections: An automatically corrected word is briefly underlined in blue. To revert to your original spelling, put the insertion point after the word to show your original spelling, then choose your spelling. You can also Control-click the word to show your spelling, then choose it.

To turn off autocorrection for a specific app, open the app, then choose Edit > Spelling and Grammar > Correct Spelling Automatically (it’s off when a tick isn’t shown).

If an app’s Edit menu doesn’t include a spelling or grammar command, check its preferences or menus to see if it has its own spell checker.

Note: To have the first word of a sentence and proper nouns (such as California or Tim) automatically capitalised as you type, select the “Capitalise words automatically” tickbox in the Text pane of Keyboard preferences.

https://support.apple.com/en-in/guide/mac-help/mchlp2299/mac

Tank you for your reply Pallavi.

This is what I meant , not in a document I am composing but , as I said, in a text I am reading. This is an example.

Hi,

You can Try this Add-on Dictionary Search .

It will surely help. Thank You.

you can look at this extension:

• macOS Dictionary Lookup https://addons.mozilla.org/firefox/addon/macos-dictionary-lookup/

Thank you all for your help, I have opted for the Macos -Dictionary option as that uses the inbuilt dictionary , great stuff. cheers, CJ