Strong's #686: ara (pronounced ar'-ah)
probably from 142 (through the idea of drawing a conclusion); a particle denoting an inference more or less decisive (as follows):--haply, (what) manner (of man), no doubt, perhaps, so be, then, therefore, truly, wherefore. Often used in connection with other particles, especially 1065 or 3767 (after) or 1487 (before). Compare also 687.
Thayer's Greek Lexicon:
̓́
ara
1) therefore, so then, wherefore
Part of Speech: particle
Relation: probably from G142 (through the idea of drawing a conclusion)
Usage:
This word is used 51 times:
Hebrews 12:8: "all are partakers, then are ye bastards, and not"