Stem has several meanings:

1. The main stalk of a plant that supports leaves, flowers, and fruit. The stem carries water and nutrients from the roots up to the rest of the plant. When you pick a flower, you're usually holding it by its stem. Some stems are thin and delicate, like on a daisy, while others grow thick and woody, like tree trunks. Celery stalks are edible stems that make a satisfying crunch.
2. To stop or slow something's flow or spread. When you stem bleeding, you're working to stop blood from flowing out of a wound. A government might try to stem the spread of a disease by closing schools temporarily. The word suggests holding back something that wants to keep moving or growing.
3. An acronym for Science, Technology, Engineering, and Mathematics. When teachers talk about STEM education, they mean learning in these four connected fields. STEM subjects often involve solving problems, building things, conducting experiments, and using logical thinking. Many schools offer special STEM programs or STEM clubs where students can work on projects like robotics, coding, or building bridges.