noun

• A branch of a family.
• (botany) The above-ground stalk (technically axis) of a vascular plant, and certain anatomically similar, below-ground organs such as rhizomes, bulbs, tubers, and corms.
  "After they are shot up thirty feet in length, they spread a very large top, having no bough nor twig in the trunk or the stem."
• (linguistics) The main part of an uninflected word to which affixes may be added to form inflections of the word. A stem often has a more fundamental root. Systematic conjugations and declensions derive from their stems.
  "The praenomen and nomen for the most part consisted of simple stems with the suffix -us or -ius, which correspond to some of the contracted forms in other languages […]."
• (slang) A person's leg.
  "She was perfectly, fuckably proportioned everywhere else, both above and below her waist. A pocket-size Venus, with the longest stems he'd ever seen on someone so dang diminutive."

verb

• (obsolete) To hit with the stem of a ship; to ram.
  "As when two warlike Brigandines at sea, / With murdrous weapons arm'd to cruell fight, / Doe meete together on the watry lea, / They stemme ech other with so fell despight, / That with the shocke of their owne heedlesse might, / Their wooden ribs are shaken nigh a sonder […]"

verb

• (transitive) To stop, hinder (for instance, a river or blood).
  "to stem a tide"
• (skiing) To move the feet apart and point the tips of the skis inward in order to slow down the speed or to facilitate a turn.

noun

• (countable, physics) Acronym of scanning transmission electron microscope.
• (uncountable, education) Acronym of science, technology, engineering, (and) mathematics.
  "Although these six classifications of the scope and responsibility and specific engineering expertise are interesting and useful, they come from within engineering itself and they don’t help us to disentangle STEM."