1. explain something very clearly
do I have to spell it out for you?
This expression refers to making something as clear or detailed as possible so that it is simple to understand. However, it is often used in a negative context as the term implies that you explain something in such a basic fashion that it is almost as if you were speaking to a child. For that reason, if somebody 'spells something out' to you, it can be insulting or patronizing. A noun or pronoun can be used between 'spell' and 'out.' It is common in both a social and professional context, and shares a similarity to the phrases 'put it simply' and 'put it in plain English.'