sad ‧ den /ˈsædn/ BrE AmE verb [transitive] formal
[ Word Family: noun : ↑ sadness , ↑ saddo ; adjective : ↑ sad , ↑ saddening ; verb : ↑ sadden ; adverb : ↑ sadly ]
to make someone feel sad:
Those who knew him are saddened by his death.
it saddens somebody that
It saddened him that they no longer trusted him.
—saddening adjective