brittle

Inflexible; liable to break, snap, or shatter easily under stress, pressure, or impact.

Not physically tough or tenacious; apt to break or crumble when bending.

(archaeology) Said of rocks and minerals with a conchoidal fracture; capable of being knapped or flaked.

Emotionally fragile, easily offended.

(engineering, computing, of a system) Poorly error- or fault-tolerant; having little in the way of redundancy or defense in depth; susceptible to catastrophic failure in the event of a relatively-minor malfunction or deviance.

(informal, proscribed) Diabetes that is characterized by dramatic swings in blood sugar level.