If a condition or problem stems from something, it was caused originally by that thing.

If you stem something, you stop it spreading, increasing, or continuing.

The stem of a plant is the thin, upright part on which the flowers and leaves grow.

The stem of a wine glass is the long thin part which connects the bowl to the base.

The stem of a pipe is the long thin part through which smoke is sucked.

In grammar, the stem of a word is the main part of it, which does not change when the ending changes.

If something happens from stem to stern on a boat, it involves the whole of the boat.