Source : Webster's Revised Unabridged Dictionary (1913)

Quintuple \Quin"tu*ple\, v. t. [imp. & p. p. {Quintupled}; p.
   pr. & vb. n. {Quintupling}.] [Cf. F. quintupler.]
   To make fivefold, or five times as much or many.

Source : WordNet®

quintupling
     n : increasing by a factor of five