DOWN is a hinge word: 11 words make a compound in front of it and 13 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 downrightMARK → DOWN → RIVER — markdown and downriverRUN → DOWN → SIDE — rundown and downsideSHOW → DOWN → STAIRS — showdown and downstairsSHUT → DOWN → STREAM — shutdown and downstreamSUN → DOWN → TIME — sundown and downtimeTAKE → DOWN → TOWN — takedown and downtownTOUCH → DOWN → TURN — touchdown and downturnKEYSTONE 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 60.
AWAY · BACK · BALL · BED · BLACK · BOARD · BOAT · BOOK · BOY · BREAK · CHECK · CROSS · DAY · DOOR · FALL · FATHER · FIRE · FOOT · GROUND · GUARD · GUN · HAND · HEAD · HOOD · HOUSE · LAND · LESS · LIFE · LIGHT · LINE · LOAD · MAN · MOTHER · NIGHT · OFF · OUT · OVER · PAY · POINT · POST · POWER · ROOM · RUN · SET · SHIP · SIDE · SOME · STEP · SUN · TAKE · TIME · TURN · UNDER · WALK · WARD · WATER · WAY · WOOD · WORK