1) Complexity 2) Ravelling 1) Fiber 2) Fibre 3) Ravelling 
• (n.) That which is raveled out; esp., a thread detached from a texture. • (n.) The act of untwisting or of disentangling. • (p. pr. & vb. n.) of Ravel
Rav'el·ing (răv''l*ĭng) noun [ Also ravelling .] 1. The act of untwisting or of disentangling. 2. That which is raveled out; esp., a thread detached from a texture. 
[n] - a bit of fiber that has become separated from woven fabric
Allowing or pulling thread to come out of the raw edge of the fabric to create a deliberate fringed look.
ravelling noun a bit of fiber that has become separated from woven fabric
Displacement of aggregate or paste near the slab surface from sawing; normally indicates that concrete strength is too low for sawing.