Synonyms for Billionth:

n.

common fraction, denominator, common denominator, And. eighth, fortieth, fourteenth, fifteenth, fifth, hundredth, fourth, eleventh, fiftieth. billionth (noun)
one-billionth, ordinal.

Other synonyms:

common fraction. common denominator, fortieth, fourteenth, eleventh, fifteenth, hundredth, fourth, eighth, fiftieth. fifth. And. Other relevant words:
hundredth, fiftieth, fourteenth, fortieth, And, eleventh, common fraction, fourth, eighth, fifth, fifteenth, denominator.