3. the act of assenting or believing: acceptance of a theory.
The word seems often used wrongly as meaning passively giving up in a bad situation i.e. resignation. A friend often accuses me of accepting things by just sitting meditating instead of trying to change injustices. Acceptance seems more positive than that. It is about fully and totally grasping all the implications of a situation, and then, and only then, (and necessarily) taking corrective action.
The 'favourable reception' definition points to opening to and staying with and embracing fully all that is present in a situation. Saying 'yes' to whatever is happening, as someone puts it.
The acceptance itself can point to a better action because we allow all the factors to sink in and be explored, whereas an avoidance reaction can be shallow and misguided.