From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

Hereafter . In   Matthew 26:64 ‘Hereafter shall ye see the Son of Man sitting on the right hand of power, and coming in the clouds of heaven,’ the meaning of ‘hereafter’ is ‘from this time’ (RV [Note: Revised Version.] ‘henceforth’). So   Mark 11:14 ,   Luke 22:69 ,   John 1:51;   John 14:30 . Elsewhere the meaning is ‘at some time in the future,’ as   John 13:7 ‘What I do thou knowest not now; but thou shalt know hereafter.’

Vine's Expository Dictionary of NT Words [2]

 John 13:7 Revelation 1:19 Revelation 4:1  Matthew 26:64 Luke 22:69  Mark 11:14Henceforward.  John 14:30 1—Timothy 1:16

Webster's Dictionary [3]

(1): ( adv.) In time to come; in some future time or state.

(2): ( n.) A future existence or state.

King James Dictionary [4]

HERE`AFTER, adv. In time to come in some future time.

1. In a future state.

HERE`AFTER,n. A future state.

'Tis heaven itself that points out an hereafter.