Can you define sex as the physical act of reproduction? For most animals its a mechanical, instinct driven activity. But for the most advanced humans, a lot of nontangible factors are thrown in (such as desire, mood,love?,…). It seems to be the best arrangement for pairing up by humans since every society has developed it. OK, given all that. How would you define sex that was outside this definition. Is it deviant sex? bad sex?
The overall question is: Is there a non religious, non legal, non societal definition of sex?