Relative magnitudes of two quantities (5)
I believe the answer is:
ratio
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">relative magnitudes of two quantities</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ratio that I've seen before include "nine-to-five, say" , "Proportion, relationship" , "Proportional relation between two numbers" , "Quotient of two numbers" , "Proporation, quantitative relation" .)