From BiblePortal Wikipedia

King James Dictionary [1]

APPE'ARING, ppr. Coming in sight becoming evident making an external show seeming having the semblance.

APPE'ARING, n. The act of becoming visible appearance.

Webster's Dictionary [2]

(p. pr. & vb. n.) of Appear

Hastings' Dictionary of the New Testament [3]

See Parousia.

International Standard Bible Encyclopedia [4]

a - pēr´ing ( ἀποκάλυψις , apokálupsis , "an unveiling"; ἐπιφάνεια , epipháneia , "a manifestation"): Exclusively technical, referring in the six passages where found to the return, the millennial advent of Christ (e.g.  1 Peter 1:7 , the King James Version;  2 Timothy 1:10;  Titus 2:13 ).