Dress clothes are clothing that is less formal than formal wear but more formal than casual wear. The term is considered a secular version of Sunday clothes and church clothes, which signifies clothes worn by some Christians to a Sunday mass.
Men's and boy's dress clothes
For boys and men, this includes items like:
Dress socks
Underwear
Trousers
Dress shoes
A dress shirt
A necktie
Women's and girls' dress clothes
For girls or women, this includes either:
Pantyhose (full cut panties are strongly recommended if one is wearing knee highs)
Knee highs
One of these three:
Slacks and a blouse or
A skirt and a blouse or
A dress
High heeled shoes
Makeup
Appropriate events and places
These are usually worn for:
Night outs
White collar work environments
Offices.
Places of worship
Graduations
Festive holidays
Thanksgiving
Christmas
Easter
Birthdays and birthday parties
Bar and Bat Mitzvahs
Visits to elegant parties
Family gatherings
Restaurant visits
Get-togethers with visiting in-laws
More formal events like:
Weddings
Funerals
Every Sunday or weekend in general (some people or families, some just during Sunday meals or similar meals).