The Collaborative International Dictionary of English v.0.48:

Mores \Mo"res\ (m[=o]"r[=e]z), n. pl.; sing. Mos (m[=o]s).
   [L.]
   Customs; habits; esp., moral customs conformity to which is
   more or less obligatory; customary law. [singular is rarely
   used]
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

mores
    n 1: (sociology) the conventions that embody the fundamental
         values of a group

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "mores":
   Weltanschauung, acculturation, amenities, bon ton, civilities,
   civility, civilization, climate, climate of opinion, comity,
   complex, conformity, consuetude, convention, courtliness,
   cultural drift, culture, culture area, culture center,
   culture complex, culture conflict, culture contact,
   culture pattern, culture trait, custom, decencies, decorum,
   dictates of society, diplomatic code, elegance, elegancies,
   established way, ethos, etiquette, exquisite manners, fashion,
   folkway, folkways, formalities, good form, good manners, ideology,
   intellectual climate, key trait, manner, manners, moral climate,
   morality, morals, natural politeness, norms, observance,
   point of etiquette, politeness, politesse, practice, praxis,
   prescription, proper thing, proprieties, protocol, punctilio,
   quiet good manners, ritual, rules of conduct, social code,
   social conduct, social convention, social graces,
   social procedures, social usage, society, spiritual climate,
   standard behavior, standard usage, standing custom,
   the conventions, the mores, the proprieties, the right things,
   time-honored practice, tradition, trait, trait-complex, usage, use,
   way, what is done, wont, wonting, world view