/məm-bəl/
interj. 1. Said when the correct response is too complicated to enunciate, or the speaker has not thought it out. Often prefaces a longer answer, or indicates a general reluctance to get into a long discussion.
"Don't you think that we could improve LISP performance by using a hybrid reference-count transaction garbage collector, if the cache is big enough and there are some extra cache bits for the microcode to use?"
"Well, mumble ... I'll have to think about it."