1) Affect 2) Become downcast 3) Bring down 4) Bring gloom upon 5) Bring on the blues 6) Bum out 7) Cast a gloom upon 8) Cause depression 9) Come to feel sad 10) Demoralize 11) Depress 12) Discourage 13) Dishearten 14) Dispirit 15) Get down 16) Impress 17) Lower 18) Make glum 19) Make melancholy 20) Make mournful Found on https://www.crosswordclues.com/clue/sadden
• (v. t.) To make grave or serious; to make melancholy or sorrowful. • (v. i.) To become, or be made, sad. • (v. t.) To make sad. • (v. t.) To render heavy or cohesive. • (v. t.) To make dull- or sad-colored, as cloth. Found on http://thinkexist.com/dictionary/meaning/sadden/
Sad'den transitive verb [ imperfect & past participle Saddened ; present participle & verbal noun Saddening .] To make sad. Specifically: (a) To render heavy or cohesive. [ Obsolete] « Marl is binding, and saddening ... Found on http://www.encyclo.co.uk/webster/S/4