A venture is a risky undertaking. If your latest venture is a dog food store, you hope there are some hungry dogs around. Also, to venture is to go somewhere possibly dangerous, like if you venture out into a snowstorm.
Venture is a shortened form of adventure. This happened sometime between 1100 AD and 1400 AD during the time that Middle English was spoken. While the two words are similar in meaning, when you subtract the "ad," you lose a teaspoon or two of fun, and add a heaping tablespoon of risk.