What is the meaning of now?

noun

• The momentary present.
  • usage: "Now is a good time to do it"; "it worked up to right now"

adverb

• In the historical present; at this point in the narration of a series of past events.
  • usage: "President Kennedy now calls in the National Guard"; "Washington now decides to cross the Delaware"; "the ship is now listing to port"
• In these times.
  • usage: "it is solely by their language that the upper classes nowadays are distinguished- Nancy Mitford; "we now rarely see horse-drawn vehicles on city streets"; "today almost every home has television"
  • synonyms: nowadays, today
• Used to preface a command or reproof or request.
  • usage: "now hear this"; "now pay attention"
• At the present moment.
  • usage: "goods now on sale"; "the now-aging dictator"; "they are now abroad"; "he is busy at present writing a new novel"; "it could happen any time now"
  • synonyms: at present
• Without delay or hesitation; with no time intervening.
  • usage: "he answered immediately"; "found an answer straightaway"; "an official accused of dishonesty should be suspended forthwith"; "Come here now"
  • synonyms: immediately, instantly, straightaway, straight off, directly, right away, at once, forthwith, like a shot
• Prefatory or transitional. ( indicates a change of subject or activity)
  • usage: "Now the next problem is..."
• In the immediate past.
  • usage: "told me just now"