Centavito is the diminutive form of centavo, meaning "little cent" or "little penny". The -ito suffix in Spanish is often used to denote smallness or affection, making the word sound more endearing.
In this song, the "little penny" is the central metaphor for fate and desperation. Romeo Santos sings "En este centavito pongo mi fe y corazón" (On this little penny I place my faith and heart), as he leaves the future of his relationship up to a simple coin toss. This powerful image of betting everything on a tiny, insignificant object makes centavito a truly unique and memorable word.
Romeo Santos takes bachata melodrama to the extreme in "Centavito," and honestly, it is wildly entertaining. He starts off completely miserable, dismissing everyone trying to help him. His doctor says his health is crashing, his mom treats his break-up like a life lesson, and he bluntly complains that his shrink "no sabe un coño del amor" [doesn't know a damn thing about love]. Even his dad tries giving old-school macho advice, claiming men don't cry and that cheating is just how men are built. Romeo rejects all of it. He cries so hard he jokes his tears could end a drought in an entire village ("con mis lágrimas no habría sequía en un pueblo").
With his bags packed and his partner standing by the door, Romeo runs out of patience and bets his entire romantic future on a literal coin toss: "Tira al viento esta moneda / Cara o cruz te vas, te quedas / Pon mi suerte en este centavito" [Toss this coin in the air / Heads or tails, you leave, you stay / Put my luck on this little penny]. The word centavito is just the diminutive form of centavo (penny), making the gamble feel delightfully desperate and tiny. He calls her "cenicienta" [Cinderella], begs for clemency, and even threatens that if she walks out, she will see him on the evening news. It is over-the-top, classic Romeo Santos pleading over a bitter, crying bachata guitar.