Advisability is whether something is a wise thing to do — whether it will keep you out of trouble, or whether the risk is too big. If a report talks about “the advisability of waiting,” it means: should we wait? Is that the sensible plan? Something advisable should be done to avoid problems; advisability is the noun for that “is it wise?” judgement. The word is stiff and formal. You will meet it in meetings, medicine, and careful writing. In real conversation people ask “Is that a good idea?” It is not a long way of saying advice. Advice is the words someone gives you. Advisability is a judgement about a plan. Though actually, writers like it because they can doubt a plan without shouting “that is stupid.”

妥當性、是否明智（偏書面；口語多半問「這樣好不好」）