sí

pronoun

1. himself, herself, itself, themself, themselves
2. yourself, yourselves

noun, masculine

1. yes; aye, ay; approbation, acceptance

interjection

1. Spain hello? (used when answering a phone call)

particle

1. yes, yeah, (used to respond affirmatively to a question, used both informally and formally)
2. Used to give positive emphasis to a verb, which is often replaced. Functions similarly to English do.