noun
US or Brit fibre , pl -bers
[noncount] :plant material that cannot be digested but that helps you to digest other food
a thin thread of natural or artificial material that can be used to make cloth, paper, etc. [count]
material (such as cloth) that is made from thin threads :something made of fibers [count]
[count] :a long, thin piece of material that forms a type of tissue in your body
[noncount] formal :strength or toughness of character
with every fiber of your being
with all of your effort or desire