boil down boil down /ˈbɔɪl daʊn/

verb

1. () Be the essential element  ( boil down , come down , reduce )
   be the essential element
    The proposal boils down to a compromise
   The proposal boils down to a compromise
   
2. (cooking) cook until very little liquid is left  ( boil down , concentrate , reduce )
   (cooking) cook until very little liquid is left
    The cook reduced the sauce by boiling it for a long time
   The cook reduced the sauce by boiling it for a long time
   
3. (cooking) be cooked until very little liquid is left  ( boil down , concentrate , decoct [Archaic] , reduce )
   (cooking) be cooked until very little liquid is left
    The sauce should reduce to one cup
   The sauce should reduce to one cup