cielo, m., heaven; sky.
cien, one hundred.
ciencia, f., science.
ciento, one hundred.
cierra, pres. of cerrar.
ciertamente, certainly, surely.
cierto,-a, certain, sure; por ——, for certain; certainly, surely.
cierto, indef. pron., a certain; some.
cigarro, m., cigar.
cinco, five.