A district is an organizing body in Toastmasters that tends to encompass a fairly large geographic area (for example, District 56 covers Houston, College Station, and Galveston in Texas). A district is typically composed of 5-6 divisions, which are made up of 5-6 areas each, which have 4-6 clubs each.
Districts have a governing body that has a number of volunteers, and put on at least one conference a year.
Sometimes roles above the club will be referred to as "district-level" in a generic sense.