Synonyms for Then:

adj.

different time (adjective)
previous, late, former, erstwhile, next, following, past, bygone, prior, future.
then (adjective)
those days, that time.

adv

accordingly (adverb)
so.
therefore (adverb)
and so.

adv.

afterward/afterwards (adverb)
late.
already (adverb)
before.
then (adverb)
so, formerly, next, when, thereupon, soon after, later, all at once, at that point, before long, years ago, suddenly.

n.

later, here, Whenever, suddenly, years ago, all, before long, soon after, at that point, when, before, This, thereupon, sometime, Until, last, formerly, all at once. then (noun)
and then, past, and so, so.

Other synonyms:

Whenever. Until, sometime, This. when, here, last. before, all. Other relevant words:
later, soon after, and then, Whenever, sometime, when, before long, so, at that point, and so, This, all, Until, formerly, all at once, thereupon, years ago, here, before, suddenly.

Usage examples for then

  1. But it was not wanted just then – Christian Mysticism by William Ralph Inge
  2. Well, then I have. – Benita, An African Romance by H. Rider Haggard