What is the meaning of then?

noun

• That time; that moment.
  • usage: "we will arrive before then"; "we were friends from then on"

adjective

• At a specific prior time.
  • usage: "the then president"

adverb

• Subsequently or soon afterward (often used as sentence connectors. )
  • usage: "then he left"; "go left first, then right"; "first came lightning, then thunder"; "we watched the late movie and then went to bed"; "and so home and to bed"
  • synonyms: so, and so, and then
• In that case or as a consequence.
  • usage: "if he didn't take it, then who did"; "keep it then if you want to"; "the case, then, is closed"; "you've made up your mind then"; "then you'll be rich"
• At that time.
  • usage: "I was young then"; "prices were lower back then"; "science as it was then taught"