Adventurer comes from the Latin root word 'Venio' alongside everyone's favorite Latin prefix 'Ad'. Venio means 'come', and Ad means 'towards or to'. Taken literally, the Latin word 'advenio' means to come to, or to come towards. From this phrase comes another similar Latin word from which we derive our modern meaning, "Adventura", which means Adventure or Venture.
In fact, Adventure and Venture are basically the same word. To Venture is "to start a risky or daring undertaking", and the literal meaning of Adventure is simply "to Venture out", or "to Venture towards". Put simply, An Adventure is simply a Venture with a goal or end result in mind.