Sumner applied the term mores to those folkways which are considered by the group to be of great significance and therefore rather indispensible to its welfare.
He writes I mean by mores the popular usages and traditions when they include a judgment that they are conducive to social welfare and when they exert coercion on the individual to conform to them although they are not coordinated by any authority.
The term mores is derived from the Latin word 'mos' which stands for customs and just as customs cannot be violated by any individual so mores also cannot be violated without incurring severe punishment. The mores relate to the fundamental needs of society more directly than do the folkways. They express the group sense of what is fitting, right and conducive to social welfare. Sumner has written the Latin word mores seems to be on the whole more practically convenient and available than any other for our purpose as a name for the folkways with the connotations of right and truth in respect to welfare embodied in them.