1
general::
dumb sth down
[ M ] informal disapproving
to make something simpler and easier for people to understand, especially in order to make it more popular
• The General Synod accused broadcasters of dumbing down religious programmes.
Cambridge-Phrasal Verbs
2
general::
adj. unable to speak VERBS be | become, be struck They were struck dumb by some sort of shock. PREP. with She sat there, dumb with rage. PHRASES deaf and dumb stupid VERBS be, feel, look, seem, sound I'm sure my question sounded really dumb. | act, play I decided to act dumb. ADV. really, very | pretty, rather
Oxford Collocations Dictionary