Note: The phrase at a venture was originally at aventure, that is, at adventure.
VENTURE
Ven"ture, v. i. [imp. & p. p. Ventured; p. pr. & vb. n. Venturing.]
1. To hazard one's self; to have the courage or presumption to do, undertake, or say something; to dare. Bunyan.
2. To make a venture; to run a hazard or risk; to take the chances. Who freights a ship to venture on the seas. J. Dryden, Jr. To venture at, or To venture on or upon, to dare to engage in; to attempt without any certainty of success; as, it is rash to venture upon such a project. "When I venture at the comic style." Waller.
VENTURE
Ven"ture, v. t.
1. To expose to hazard; to risk; to hazard; as, to venture one's person in a balloon. I am afraid; and yet I'll venture it. Shak.
2. To put or send on a venture or chance; as, to venture a horse to the West Indies.
3. To confide in; to rely on; to trust. [R.] A man would be well enough pleased to buy silks of one whom he would not venture to feel his pulse. Addison.
VENTURER
Ven"tur*er, n.
1. One who ventures, or puts to hazard; an adventurer. Beau. & Fl.