Structural Hazard: a possible interruption to a computation or flow of data owing to a physical resource that has insufficient capacity. Consequently, operations that could potentially be done in parallel have to be done serially.
A Non-fully pipelined component: is unable to start a new operation on every clock cycle.
Such a component:
Example: fixed point multipliers and dividers (see additional material).
Example: all floating point operations tend to be implemented with multi-cycle units.