Synonyms for Belittle:

n.

trivialize, eclipse, overshadow. deprecate, downgrade, detract, show, talk down, attack, slight, run down. belittle (noun)
pick at, diminish, disparage.

v.

cheapen (verb)
deflate, cheapen, depreciate, discount, devalue, debase, degrade, pare, diminish, mark down, shave, devaluate, trim, slash, reduce, cut.
detract (verb)
diminish, downgrade, depreciate, underestimate, deprecate, discount, run down, undervalue, lower, disparage.
lower (verb)
deprecate, study at depreciate.
shorten (verb)
clip, abridge, lower, shorten, condense, compact.
underestimate (verb)
underestimate, undervalue.

Other synonyms:

detract. downgrade. cheapen
mark down.
deplore
deprecate.
ridicule
run down.
Other relevant words:
detract, overshadow, slight, deprecate, trivialize, eclipse, attack, show, pick at, disparage, talk down, downgrade.