sino
/ˈsino/ · A2 · conj
but
sino = si + no: if not this, then rather that
Sino fuses si (if) and no (not): No es rojo sino azul = not red, if-not-that then blue. The noun sino (fate) is a separate word, from Latin signum (sign), the same root as signo: your lot is what the signs marked out.