What does again mean?
The definition of again
A*gain”, adv.
Etym: [OE. agein, agayn, AS. ongegn, ongeán, against, again; on + geán, akin to Ger. gegewn against, Icel. gegn. Cf. Gainsay.]

1 In return, back; as, bring us word again.
2 Another time; once more; anew. If a man die, shall he live again Job xiv. 14.
3 Once repeated; — of quantity; as, as large again, half as much again.
4 In any other place. [Archaic] Bacon.
5 On the other hand. “The one is my sovereign . . . the other again is my kinsman.” Shak.
6 Moreover; besides; further. Again, it is of great consequence to avoid, etc. Hersche Again and again, more than once; often; repeatedly.

— Now and again, now and then; occasionally.
— To and again, to and fro. [Obs.] De Foe.
Note: Again was formerly used in many verbal combinations, as, again- witness, to witness against; again-ride, to ride against; again-come, to come against, to encounter; again-bring, to bring back, etc.