Just think of the phrase Defying MURmur formed from by splitting the word demur into two parts-De and Mur.
A sentence to remember this better-“The defying murmur in the audience rose to a demur against the manager’s suggestion.
[dɪˋmɝ]
The word demur means to object or oppose.
Your mother asks you to pick up your room. You refuse: you demur.
Your friend wants to go to the Death Metal Forever concert, but you hesitate: you demur.
Whether you strongly object, politely disagree, or hesitate to agree, you demur.
And if you find yourself the defendant in a civil suit, you might file a demurrer to object to the plaintiff’s complaint. When you file that demurrer, you demur.