the evil red line

the evil red line

How can I turn off the red line that appears under words that Zoho does not like? I notice that more than spelling is involved, it includes capitalization and whatever else. It does not know brand names, technology words, peoples' names, etc. In fact, in this message it is flagging -- Zoho.

How do I get rid of the nagging red line that infects ten or twenty percent of the words in my documents?