Precipitant

Pre*cip"i*tant (?), a. [L. praecipitans, -antis, p. pr. of praecipitare: cf. F. précipitant. See Precipitate.] 1. Falling or rushing headlong; rushing swiftly, violently, or recklessly; moving precipitately.

They leave their little lives
Above the clouds, precipitant to earth.
J. Philips.

Should he return, that troop so blithe and bold,
Precipitant in fear would wing their flight.
Pope.

2. Unexpectedly or foolishly brought on or hastened; rashly hurried; hasty; sudden; reckless. Jer. Taylor. "Precipitant rebellion." Eikon Basilike.

Pre*cip"i*tant, n. (Chem.) Any force or reagent which causes the formation of a precipitate.