Discretion, n.
Etymology: [F. discrétion, L. discretio separation, difference, discernment, fr. discernere, discretum. See Discreet, Discern.]
1. Disjunction; separation. [Obs.] Mede.
2. The quality of being discreet; wise conduct and management; cautious discernment, especially as to matters of propriety and self- control; prudence; circumspection; wariness. The better part of valor is discretion. Shak. The greatest parts without discretion may be fatal to their owner. Hume.
3. Discrimination. Well spoken, with good accent and good discretion. Shak.
4. Freedom to act according to one's own judgment; unrestrained exercise of choice or will. At discretion, without conditions or stipulations.
Shades of meaning
Fernald has no entry of its own for discretion; he lists it under address, prudence, wisdom.
Where he writes about it:
It includes adroitness and discretion to know what to do or say and what to avoid; ingenuity to devise; readiness to speak or act; the dexterity that comes of practise; and tact, which is the power of fine touch as applied to human character and feeling. — from address