Definition of "conventional"

conventional

/kənˈvɛnʃənəl/

adjective
comparative more conventional, superlative most conventional
1. Pertaining to a convention, as in following generally accepted principles, methods and behaviour.
  Quotations
  A “moving platform” scheme […] is more technologically ambitious than maglev trains even though it relies on conventional rails. Local trains would use side-by-side rails to roll alongside intercity trains and allow passengers to switch trains by stepping through docking bays.
  2013 June 1, “Ideas coming down the track”, in The Economist, volume 407, number 8838, page 13 (Technology Quarterly)
2. Ordinary, commonplace.
  Quotations
  “You’re not conventional?” Isabel gravely asked. “I like the way you utter that word! No, I’m not conventional: I’m convention itself. You don’t understand that?”
  1908, Henry James, chapter XXIX, in The Portrait of a Lady (The Novels and Tales of Henry James; IV), New York edition, volume II, Boston, Mass., New York, N.Y.: Charles Scribner’s Sons; republished as The Portrait of a Lady (EBook #2834), United States: Project Gutenberg, 1 September 2001
  Mother […] considered that the exclusiveness of Peter's circle was due not to its distinction, but to the fact that it was an inner Babylon of prodigality and whoredom, from which every Kensingtonian held aloof, except on the conventional tip-and-run excursions in pursuit of shopping, tea and theatres.
  1922, Ben Travers, chapter 2, in A Cuckoo in the Nest‎
  The history of our study of our solar system shows us clearly that accepted and conventional ideas are often wrong, and that fundamental insights can arise from the most unexpected sources.
  1980, Carl Sagan, Cosmos: A Personal Voyage
3. Banal, trite, hackneyed, unoriginal or clichéd.
4. (weaponry) Pertaining to a weapon which is not a weapon of mass destruction.
5. (agriculture) Making use of synthetic fertilizers and pesticides.
6. (bridge) In accordance with a bidding convention, as opposed to a natural bid.
noun
plural conventionals
1. (finance) A conventional gilt-edged security, a kind of bond paying the holder a fixed cash payment (or coupon) every six months until maturity, at which point the holder receives the final payment and the return of the principal.