This weekend, I rode (and sometimes walked) the most technical trail I've ever ridden and thought of another definition (for me anyway): If I sweat more because I'm taking risks* and nervously pushing my skill limits than because of the aerobic/strength challenge, then it's probably technical.

*small ones, like "I might fall on those rocks", not "I might fall off a cliff and die". I'm pretty cautious and don't like heights.