Synonyms for Then:

adj.

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

adv

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

adv.

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

n.

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

Other synonyms:

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

Usage examples for then

  1. That's the last we will see of the place, then – The Hilltop Boys on Lost Island by Cyril Burleigh
  2. But it was not wanted just then – Christian Mysticism by William Ralph Inge
  3. Well, then I have. – Benita, An African Romance by H. Rider Haggard