Bombilation is a rare word meaning a buzzing or humming sound. However, if you need some alternative synonyms to avoid overusing or sounding repetitive, there are some options available. One alternative could be the word "vibration," which communicates a similar sound effect. "Murmur" can also be used depending on the context, although it refers to a quieter noise. "Buzz" is another common term that can substitute bombilation, particularly when describing insect activity. Other potential synonyms include "drone," "humming," "whirring," and "whizzing," all of which suggest a constant or repeated sound. The key is to choose a synonym that best fits the context and situation you are writing about.