Synthetic viability is when two things that don't work alone are able to work together to survive. Think of it like when you and your best friend play together. You might not be able to have as much fun on your own, but when you're together, you can have more fun and help each other out.
In science, synthetic viability happens when two different genes or proteins that are both necessary for survival can work together to keep an organism alive. It's like when two puzzle pieces fit together perfectly to make a whole picture.
Scientists study synthetic viability to learn more about how different parts of our bodies work together to keep us healthy, and to try to find new ways to treat diseases. By understanding how different genes and proteins can work together, scientists can develop new treatments that target multiple parts of the body at once, instead of just treating one part at a time.