A progenitor is an ancestor or the originator of something. Your great-great-great-grandmother is one of your progenitors: someone from whom you are directly descended. The word goes beyond just “ancestor,” though. It carries a sense of being the first or the founder of a line.

Scientists use progenitor to describe the original source of something that came after. The progenitor of all modern wolves, dogs, and foxes was an ancient wolf-like creature that lived millions of years ago. In biology, a progenitor cell is a cell that gives rise to more specialized cells, like how a single seed can become the progenitor of an entire apple orchard.

The word works for ideas and inventions too. Ancient Greek philosophers like Aristotle were progenitors of scientific thinking: they originated methods and questions that scientists still use today. The Wright brothers were progenitors of modern aviation. When historians call someone a progenitor, they're saying, “This is where it all started. Everything that came after traces back to this beginning.”