It's been too long since I've posted a plain and simple derivative post...so here goes.
frangere (L) - to break (4th PP: fractus)
fraction (n) - a piece that is broken off from the whole
fractious (adj) - prone to break the peace; unruly; quarrelsome (fractiousness)
fragment (n) - a broken piece (fragmentation, fragmented, fragmentize, fragmentizer)
infract (v) - to break by violating (infraction, infractor)
refract (v) - to break repeatedly (refractive, refractory, refraction, refractivity)
fragile (adj) - easily broken (fragility)
infringe (v) - to break a barrier; to trespass (infringement)
Can you add to this list?