1st (first) =

primero

2nd (second) =

segundo

3rd (third) =

tercero

4th (fourth) =

cuarto

5th (fifth) =

quinto

6th (sixth) =

sexto

7th (seventh) =

séptimo, sétimo

8th (eighth) =

octavo

9th (ninth) =

noveno

10th (tenth) =

décimo

11th (eleventh) =

undécimo

12th (twelth) =

duodécimo