negligible

definition: 
So small or unimportant as to be not worth considering; insignificant:
sentence: 
The amount of bacteria in the culture was negligible
difficulty: 
very easy
toefl frequency: 
3
toefl classification: 
adverb: 
negligibly
adjective: 
adverb sentence: 
The researchers say that a shell of plasmonic material will scatter light negligibly if the light's frequency is close to the resonant frequency of the plasmons.
adjective sentence: 
verb: 
verb sentence: 
noun: 
negligence
noun sentence: 
Some of these accidents are due to negligence
The negligence caused me to lose all of the work I had worked on