Precipitance, Precipitancy, n.
Etymology: [From Precipitant.]
The quality or state of being precipitant, or precipitate; headlong hurry; excessive or rash haste in resolving, forming an opinion, or executing a purpose; precipitation; as, the precipitancy of youth. "Precipitance of judgment." I. Watts.
Shades of meaning
Fernald has no entry of its own for precipitancy; he lists it under temerity.
He lists it without comment; the entries above explain its neighbors.