Now \Now\, adv. [OE. nou, nu, AS. n[=u], nu; akin to D., OS., & OHG. nu, G. nu, nun, Icel., n[=u], Dan., Sw., & Goth. nu, L. nunc, Gr. ?, ?, Skr. nu, n[=u]. [root]193. Cf. New.]

1. At the present time; at this moment; at the time of speaking; instantly; as, I will write now.

I have a patient now living, at an advanced age, who discharged blood from his lungs thirty years ago. --Arbuthnot.

2. Very lately; not long ago.

They that but now, for honor and for plate, Made the sea blush with blood, resign their hate. --Waller.

3. At a time contemporaneous with something spoken of or contemplated; at a particular time referred to.

The ship was now in the midst of the sea. --Matt. xiv. 24.

4. In present circumstances; things being as they are; -- hence, used as a connective particle, to introduce an inference or an explanation.

How shall any man distinguish now betwixt a parasite and a man of honor ? --L'Estrange.

Why should he live, now nature bankrupt is ? --Shak.

Then cried they all again, saying, Not this man, but Barabbas. Now, Barabbas was a robber. --John xviii. 40.

The other great and undoing mischief which befalls men is, by their being misrepresented. Now, by calling evil good, a man is misrepresented to others in the way of slander. --South.

Now and again, now and then; occasionally.

Now and now, again and again; repeatedly. [Obs.]

--Chaucer.

Now and then, at one time and another; indefinitely; occasionally; not often; at intervals. ``A mead here, there a heath, and now and then a wood.'' --Drayton.

Now now, at this very instant; precisely now. [Obs.]

``Why, even now now, at holding up of this finger, and before the turning down of this.'' --J. Webster (1607).

Now . . . now, alternately; at one time . . . at another time. ``Now high, now low, now master up, now miss.'' --Pope.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Then \Then\ ([th][e^]n), adv. [Originally the same word as than. See Than.]

1. At that time (referring to a time specified, either past or future).

And the Canaanite was then in the land. --Gen. xii. 6.

Now I know in part; but then shall I know even as also I am known. --1 Cor. xiii. 12.

2. Soon afterward, or immediately; next; afterward.

First be reconciled to thy brother, and then come and offer thy gift. --Matt. v. 24.

3. At another time; later; again.

One while the master is not aware of what is done, and then in other cases it may fall out to be own act. --L'Estrange.

By then.
   (a) By that time.
   (b) By the time that. [Obs.]

But that opinion, I trust, by then this following argument hath been well read, will be left for one of the mysteries of an indulgent Antichrist. --Milton.

Now and then. See under Now, adv.

Till then, until that time; until the time mentioned. --Milton.

Note: Then is often used elliptically, like an adjective, for then existing; as, the then administration.

Source: Webster's Revised Unabridged Dictionary (1913)