ordinal numbers

thirty

thir·ty /ˈɵɚti/ noun, pl -ties
1 [count] : the number 30
2 thirties [plural]
a : the numbers ranging from 30 to 39
• The temperature outside is in the high thirties.
b : a set of years ending in digits ranging from 30 to 39
• He is in his thirties.
• old photographs from the thirties [=from 1930–1939]
- thir·ti·eth /ˈɵɚtijəɵ/ noun, pl -tieths [count]
• the thirtieth of November
• seven thirtieths of a degree
- thirtieth adj
• her thirtieth birthday
- thirty adj
• thirty days/dollars
- thirty pronoun
• thirty of his classmates
- thir·ty·ish /ˈɵɚtijɪʃ/ adj
• He was tall, thirtyish [=about 30 years old], and had glasses and brown hair.

twenty

twen·ty /ˈtwɛnti/ noun, pl -ties
1 [count] : the number 20
2 [count] : the 20th in a set or series
• item/question twenty
3 twenties [plural]
a : the numbers ranging from 20 to 29
• Tomorrow the temperature will be in the low twenties.
b : a set of years ending in digits ranging from 20 to 29
• She's in her twenties.
• the gangsters of the twenties [=of the 1920s]
4 [count]
a US : a twenty-dollar bill
• All I have is a twenty.
b Brit : a twenty-pound note
- twen·ti·eth /ˈtwɛntijəɵ/ noun, pl -eths [count]
• What are you doing on the twentieth? [=the twentieth day of the month]
• a twentieth of the population
- twentieth adj
• their twentieth anniversary
- twenty adj
• It was a twenty-hour flight.
• twenty days later
- twenty pronoun
• Only twenty showed up for the review session.
• We spent forty dollars and had twenty left.

thirteen

thir·teen /ˌɵɚˈtiːn/ noun, pl -teens [count] : the number 13
- thirteen adj
• thirteen students
- thirteen pronoun
• All thirteen (of them) passed the exam.
- thir·teenth /ˌɵɚˈtiːnɵ/ noun, pl -teenths [count]
• the thirteenth of October
• one thirteenth of the budget
- thirteenth adj
• the thirteenth caller
- thirteenth adv
• She finished thirteenth.
• the nation's thirteenth largest city

twelfth

²twelfth adj : occupying the number 12 position in a series
• the twelfth day in a row
• finished in twelfth place
- twelfth adv
• Our son finished twelfth in the race.
• the twelfth best-selling book

eleven

elev·en /ɪˈlɛvən/ noun, pl -ens
1 [count] : the number 11
2 [count] : the eleventh in a set or series
• page eleven
• item/question number eleven
3 [noncount] : eleven o'clock
• I got home last night at eleven.
- eleven adj
• eleven turtles
- eleven pronoun
• Eleven (of them) were absent from the ceremony.
- elev·enth /ɪˈlɛvənɵ/ noun, pl -enths [count]
• one eleventh of the total
- eleventh adj
• the eleventh person in line
- eleventh adv
• He finished eleventh in the race.

tenth

²tenth adj : occupying the number ten position in a series
• This year is our tenth wedding anniversary.
• the tenth grade
- tenth adv
• the world's tenth largest country

ninth

²ninth adj : occupying the number nine position in a series
• on the ninth day
• the book's ninth edition
• She's in (the) ninth grade at school.
- ninth adv
• He finished ninth in the race.
• the country's ninth largest city

eighth

²eighth adj : occupying the number eight position in a series
• the eighth car in line
• the eighth edition
• Her son is in (the) eighth grade.
- eighth adv
• She finished eighth (in the race).

seventh

²seventh adj : occupying the number seven position in a series
• on the seventh day
• the book's seventh edition
• her seventh goal of the season
• I finished in seventh place in the competition.
- seventh adv
• She finished seventh in the race.
• the nation's seventh largest city