The Spanish letter ñ appears in quinceañera but not in the English spelling quinceanera.
The tilde over the n is not decorative: ñ is a distinct letter in Spanish. In quinceañera, it represents the palatal nasal sound heard in Spanish words such as mañana. The spelling therefore preserves an important feature of the original language.
English-language writing often drops the tilde when keyboards or publishing systems make accented characters difficult to enter. “Quinceanera” remains recognizable, but “quinceañera” is the standard Spanish spelling. The same issue appears with other Spanish words containing ñ, including niño and año.
The letter also helps prevent ambiguity in Spanish. Año means “year,” while ano is a different word, so the tilde can change meaning. In the celebration’s name, retaining ñ accurately reflects Spanish pronunciation and orthography.