Nie, dumb znaczy niemy. Chyba że jesteś lepiej poinformowany niż twórcy Oxford dictionary, ale raczej wątpię.
adjective, dumber, dumbest.
1.
lacking intelligence or good judgment; stupid; dull-witted.
2.
lacking the power of speech (offensive when applied to humans):
a dumb animal.
3.
temporarily unable to speak:
dumb with astonishment.
4.
refraining from any or much speech; silent.
5.
made, done, etc., without speech.
6.
lacking some usual property, characteristic, etc.
7.
performed in pantomime; mimed.
