In legal terms, a proviso is a thing added to an agreement or document that’s detailing the terms. For example, you may agree to buy a motorcycle with a proviso that the leather bags are included as part of the deal.
The word “proviso” has its origins in the Latin verb “providere” which means “foresee or provide” and the similarity with words like “provision” and “provide” is obvious. Proviso generally implies that getting or buying something includes conditions or is conditional. Just look at the following example. You agree to accompany your younger sister to the movies, provided (“with the proviso”) that you’ll get popcorn and a 40-ounce soft drink as well. Well, I guess that many parents could agree to this proposal “with the proviso” that your drink is no bigger than 20 ounces. Deal?