Lastro

Lastro is a Portuguese word that translates directly to "ballast" in English. It refers to heavy material, such as rocks, sand, or metal, used to stabilize a ship or other vessel. The purpose of ballast is to lower the center of gravity and increase the vessel's stability, preventing it from capsizing, especially when it is carrying a light or uneven load.

In a figurative sense, "lastro" can also refer to something that provides stability or weight to a situation, idea, or project. It can represent a grounding force, a solid foundation, or something that lends credibility or seriousness. For example, one might say that a thorough investigation provides "lastro" to an argument, meaning it strengthens the argument and makes it more credible.

Historically, the type of material used as lastro was often chosen for its availability and density. Ships would often load ballast at one port and unload it at another. The practice of discharging ballast can sometimes have environmental consequences, particularly if the ballast contains invasive species. Modern ships often use ballast water tanks instead of solid materials to control trim and stability.