Synonyms for Conventional:

adj.

accepted (adjective)
approved, established, prevalent, traditional, sanctioned, accepted, standard, orthodox, customary, Condoned.
all (adjective)
established.
average (adjective)
medium, mid, halfway, usual, average, midmost, run-of-the-mill, normal, commonplace, customary, dominant, mean, mezzo, middling, stereotype, standard, everyday, median, predominant, ordinary, stock, moderate, middle-of-the-road, common, mediocre.
conforming (adjective)
obedient, regular, submissive, formal, customary, conformist, correct, consist, complying, Adhering, proper, Aping, mannerly, conforming, Acquiescing, traditional, congruous.
habitual (adjective)
recurrent, common, Acclimated, custom, regular, Familiar, conditioned, accustomed, habitual, well-worn, routine, timeworn.
hackneyed (adjective)
timeworn, well-worn.
orthodox (adjective)
buttoned-down.
received (adjective)
received.
regular (adjective)
orthodox, usual, everyday, average, cyclical, continual, ordinary, recurrent, stock, frequent, monotonous, metronomic, traditional, common, prevailing, steady, commonplace, normal, canonical, standard, general, chronic, universal, accustomed, periodic, Predominating, constant, habitual, epochal, routine, customary, rhythmic, regular, mundane, Familiar.
unexceptional (adjective)
unexceptional.
unoriginal (adjective)
hidebound, conforming, inflexible, moderate, narrow-minded, parochial, run-of-the-mill, illiberal, literal, dogmatic, obstinate, insular, puritanical, conservative, bigoted, narrow, strict, stuffy, rigid.
wonted (adjective)
expected.

n.

antenatal, clear, bloodless, combination, antibacterial, clinical, bionic, aseptic, accept, broad-spectrum, recognized, agree, antimalarial. Establishmentarian. courtesy, punctilious. conventional (noun)
conservative, stodgy, traditional, buttoned-down, stereotypical, stereotyped, square, formulaic, schematic, received, stereotypic, accepted, orthodox, button-down, unimaginative, established, stuffy, straight, ceremonious, customary, nonrepresentational.

Other synonyms:

ceremonial, nonnuclear, anti-personnel, Establishmentarian, anti-tank, antiaircraft, decent. narrow, recognized, long-range, popular. punctilious. live. explosive. heavy. bigoted
narrow-minded.
characteristic
typical.
narrow-minded
parochial.
old fashioned
square.
ordinary
plain.
usual
wonted.
wonted
expected.

Usage examples for conventional

  1. Angel cast a final glance round, and then going to the foot of the stairs, called in a conventional voice- " Breakfast is ready!" – Tess of the d'Urbervilles A Pure Woman by Thomas Hardy
  2. Charles did not remember having read this sentence in the address which had been submitted to him some days before; but he attached no importance to Marguerite's words, which he knew were merely conventional – Marguerite de Valois by Alexandre Dumas
  3. They find no difficulty in using the conventional style of address of " May it please the Court," or " May it please your Honor." – The American Judiciary by Simeon E. Baldwin, LLD