From convention + -al.

• IPA: /kənˈvɛnʃənəl/

conventional

1. Pertaining to a convention, as in following generally accepted principles, methods and behaviour.
2. Ordinary, commonplace.

   They wear conventional clothes, eat conventional food, and keep conventional hours.

   • 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, →OCLC ↗; republished as The Portrait of a Lady (EBook #2834), United States: Project Gutenberg, 1 September 2001:

     “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?”

   • 1921, Ben Travers, chapter 2, in A Cuckoo in the Nest, Garden City, N.Y.: Doubleday, Page & Company, published 1925, →OCLC ↗:

     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.

   • 1980, Carl Sagan, Cosmos: A Personal Voyage:

     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.

3. Banal, trite, hackneyed, unoriginal or clichéd.
4. (weapons) 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.

   Synonyms: artificial

   Antonyms: natural

• (pertaining to a convention) typical, canonical
• (banal) stereotypical

• (antonym(s) of “pertaining to a convention”): atypical, out of the ordinary, unconventional
• (antonym(s) of “ordinary”): imaginative
• (antonym(s) of “weapons”): nuclear
• (antonym(s) of “agriculture”): organic
• (antonym(s) of “bridge”): natural

• convention

• French: conventionnel
• German: konventionell
• Portuguese: convencional
• Russian: общепри́нятый
• Spanish: convencional

• French: conventionnel
• German: konventionell, herkömmlich
• Italian: convenzionale
• Portuguese: convencional
• Russian: обы́чный
• Spanish: convencional

conventional (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.