When you boil down a liquid or food, or when it boils down, it is boiled until there is less of it because some of the water in it has changedinto steam or vapour.
He boils down the sauce and uses what's left. [VERBPARTICLE noun]
This may seem a large quantity of mushrooms, but they do boil down considerably. [VERBPARTICLE]
See full dictionary entry for boil
boil down in British English
verb(adverb)
1.
to reduce or be reduced in quantity and usually altered in consistency by boiling
to boil a liquid down to a thick glue
2. boil down to
boil down in American English
1.
to lessen in quantity by boiling, esp. so as to change consistency
2.
to make more terse; condense; summarize
See full dictionary entry for boil
Examples of 'boil down' in a sentence
boil down
`You must realise that, in your predicament, when you have too much fear, even the infinite outcomes boil down to two basic ones.
Scarlett Thomas GOING OUT (2002)
I wondered how forty years of life could suddenly boil down to a lesson in triage.