倍率【ばいりつ】
magnification, leverage, amplification, scaling factor, scale factor, competitiveness rating (e.g. for university entrance), applicant-to-acceptance ratio
倍増【ばいぞう】
doubling, double
一倍【いちばい】
multiplying by one, original amount, (even) more, double, twice (as much), twofold
倍加【ばいか】
doubling, marked increase, multiplying, redoubling