thirty-ninth UK /ˌθɜːti ˈnaɪnθ/US /ˌθɚti ˈnaɪnθ/adjective 1noun 1forms 1 adjective1 •The ordinal form of the number thirty-nine, describing a person or thing in position number 39 of a sequence.The answer appears on the thirty-ninth page of the book.She finished thirty-ninth in the race. noun1 •One of thirty-nine equal parts of a whole.A thirty-ninth of 780 is 20. formsthirty-ninths