Vowel that is added to some stems, before the endings. This morpheme is necessary in some cases for a word to receive endings or suffixes. They are classified in nominal and verbal. Nominal thematic vowels are vowels such as -a-, -o- or -e-, which in Italian, Spanish and Portuguese are added to penult or antepenult words, as Port. casa, caderno or cidade. In turn, verbal thematic vowels are vowels such as -a-, -e- or -i-, which, added to verbal stems, form the conjugations. In Spanish and Portuguese we have: 1st conjugation: amar; 2nd conjugation: correr; 3rd conjugation: dormir.