Refraining from believing that circumstances could or should conform to our satisfaction.
From Neurotic Gradient Descent: (mis)Translating the Buddha
So Nicca is our tendency to believe that things could or should be maintained to our satisfaction. This is an identifiable mental event in how we reify an object or concept. Ignoring the very ephemeral nature of moment to moment experience in favor of only noticing those aspects which do occur as stable. Spotting it for yourself is very powerful. If this were just considered on its own without the teaching of the antidote it might be related to feelings of hopelessness. That there is no hope of maintaining the conditions that lead to things we like. Thus, the flow of positive and negative experiences are undependable, indefinite in duration, intensity, and frequency. That our hopes of forcing them to be stable with our mind will be in vain.