a combining form occurring in loanwords from Greek and Latin, where it meant “eight” (octagon; octastyle), on this model, used in the formation of compound words, and in chemical terms specialized to mean “having eight atoms” (octavalent).
Also oct-, octo-.

Origin of octa-

< Greek okta-, combining form of oktṓ eight
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for octa

  • The incautious sovereign having assented to this, Octa and Ebusa arrived with forty ships.

  • After this Eosa and the rest that fled, being encouraged by Octa's success, came also, and were admitted to the same favour.

British Dictionary definitions for octa (1 of 2)


/ (ˈɒktə) /


a variant spelling of okta

British Dictionary definitions for octa (2 of 2)


combining form

a variant of octo-
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012