Idempotent. But non-trivial does have a specific meaning: it means that we don't have any code already written or proven technique that we can simply reuse for or apply to this problem, and some new knowledge will have to be synthesized, and there's a risk in making any estimates of time/cost until more is known.
What's wrong with idempotent? It has a precise, useful meaning
Re: Ask HN: What's your least favorite tech word? Mine's "non-trivial".
#31It's often misused. Along with orthogonal.