noun

• (cooking, painting, pharmacy) A basic but essential component or ingredient.
• (cosmetics) Foundation: a cosmetic cream to make the face appear uniform.
• (chemistry) Any of a class of generally water-soluble compounds that turn red litmus blue and react with acids to form salts.
• Important areas in games and sports.

verb

• (transitive) To give as its foundation or starting point; to lay the foundation of.
  "Firstly, I continue to base most species treatments on personally collected material, rather than on herbarium plants."
• (transitive) To be located (at a particular place).
  "Take a look at that. This is where we are going to be basing this season."
• (acrobatics, cheerleading) To act as a base; to be the person supporting the flyer.
  "Apart from time taken out during radio- and chemotherapy, Maurs continued to participate in POW. She would base a flyer in a double balance and make the audience laugh with her clowning antics for two more shows."
• (slang) To freebase.
  "You know he started to base at a hell of a pace / And now it's a disgrace, he's got the pipe in his face"

adj

• (obsolete) Low in height; short.
  "The cedar stoops not to the base shrub's foot."
• (obsolete) Of low value or degree.
  "If thou livest in paine and sorrow, thy base courage is the cause of it, To die there wanteth but will."
• (archaic) Of low social standing or rank; vulgar, common.
  "UUhat meanes the mightie Turkiſh Emperor To talke with one ſo baſe as Tamburlaine?"
• (now rare) Inferior; unworthy, of poor quality.
  "'Like this horrible film.' 'Horrible?' Lenina was genuinely astonished. 'But I thought it was lovely.' 'It was base,' he said indignantly, 'it was ignoble.'"

noun

• (now chiefly US, historical) The game of prisoners' bars.
  "to run the country base"