DOWN is a hinge word: 10 words make a compound in front of it and 11 make one after it, so it can sit in the middle of a chain and hold two compounds together at once.
Each of these makes a compound ending in DOWN.
Each of these makes a compound starting with DOWN.
DOWN is a direction, so it behaves like OUT and OVER: it attaches to verbs on either side. A SHUTDOWN and a DOWNPOUR use the same particle in opposite positions.
Put any word from the first list in front and any word from the second behind, and you have a three-word chain in which both neighbouring pairs join. Here are some of them.
BREAK → DOWN → FALL — breakdown and downfallCOUNT → DOWN → HILL — countdown and downhillLET → DOWN → LOAD — letdown and downloadLOW → DOWN → RIGHT — lowdown and downrightRUN → DOWN → RIVER — rundown and downriverSHOW → DOWN → SIDE — showdown and downsideSHUT → DOWN → STAIRS — shutdown and downstairsSUN → DOWN → TIME — sundown and downtimeTAKE → DOWN → TOWN — takedown and downtownTOUCH → DOWN → WARD — touchdown and downwardKEYSTONE is a free daily puzzle built entirely out of chains like these. You get the two ends and have to fill the two words in the middle. Three bridges a day, no account, no cookies.
Each of these has a page like this one. There is also an index of all 28.
BACK · BALL · BED · BOARD · BOOK · BREAK · DAY · FALL · FIRE · GUN · HAND · HEAD · HOUSE · LAND · LIFE · LIGHT · MAN · NIGHT · OFF · OUT · OVER · SHIP · SIDE · SOME · TIME · WAY · WORK