The Spanish verb sentir (to feel) is semi-regular since the stem changes in some forms El Presente, but it has regular ‑ir group endings:
| yo |
siento |
| tú |
sientes |
| él / ella / Ud. |
siente |
| nosotros / nosotras |
sentimos |
| vosotros / vosotras |
sentís |
| ellos / ellas / Uds. |
sienten |
Notice how for all three groups, the first vowel -e- in the stem becomes-ie- except for the nosotros and vosotros forms.
Sentir used on its own can mean to be sorry / to feel sorry.
Look at and listen to these examples:
Yo siento que esta idea va a ser un éxito.I feel that this idea is going to be a success.
¿Tú no sientes nada por ella?Do not you feel anything for her?
Él siente una gran alegría.He feels great joy.
Nosotros sentimos que no vengas con nosotros.We're sorry that you're not coming with us. [lit: we feel that]
Vosotros sentís un gran amor por la naturaleza.You feel a great love for nature.
Ellos sienten muchas agujetas en las piernas después de la escalada.They feel a lot of stiffness in their legs after climbing.
See also:
List of Common Spanish stem-changing (e > ie) verbs in the present tenseYo siento que esta idea va a ser un éxito.I feel that this idea is going to be a success. Ellos sienten muchas agujetas en las piernas después de la escalada.They feel a lot of stiffness in their legs after climbing. Él siente una gran alegría.He feels great joy. Nosotros sentimos que no vengas con nosotros.We're sorry that you're not coming with us. [lit: we feel that] Vosotros sentís un gran amor por la naturaleza.You feel a great love for nature. ¿Tú no sientes nada por ella?Do not you feel anything for her? 
