Fifteenth/ˌfɪfˈtiːnθ/ Definition 1 of 4Pro Tip 1/3Ordinal Position Indicates order within a sequence, specifically the number after fourteenth. He finished in fifteenth place in the race. Pro Tip 2/3Historical Periods Often used to denote centuries and specific historical time frames. Gothic architecture was prominent in the fifteenth century. Pro Tip 3/3Not Numerical Although related to numbers, it represents a place in order, not a count of items. My favorite poem is the fifteenth in the collection.