STEM - [noun] the part of a plant from which leaves grow or something that has similar shape
Examples of use
The wind has broken the stems of all flowers in my garden.
Hold the glass wine by the stem rather than the bowl not to leave fingerprints on it.
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English speaking practise
Remember that if you don't use that word in English conversations or writing you'll forget it in a short time. So the best thing you can do to learn this word is just trying to use it in speaking or writing. Remember also that practise is the key to fluent english speaking.
You can always find a partner, who would also like to improve his/her