<p>I have a team lead who seems to think that business logic is very subjective, to the point that if my stored procedure has a <code>WHERE ID = @ID</code> — he would call this <em>“business logic”</em></p>

<p>What approach should I take to define <em>“business logic”</em> in a very objective way without offending my team lead?</p>

I really think you just need to agree on a clear definition of what you mean when you say "business logic".  If you need to be "politically sensitive", you could even craft the definition around your team lead's understanding, then come up with another term ("domain rules"?) that defines what you want to talk about.
Words and terms are relatively subjective -- of course, once you leave that company you will need to 're-learn' industry standards, so it's always better to stick with them if you can, but the main goal is to communicate clearly and get work done.