1) Appropriative 2) Of a certain bridge bid 3) Preventative 4) Preventive 1) Preventative 
Describes an operating system where the task-switching operation can occur at any point. The kernel can preempt the operation of any process in order to switch tasks. The process need not relinquish control or signify in any way that it is ready to be switched. 
• (a.) Of or pertaining to preemption; having power to preempt; preempting.
Pre·ëmp'tive adjective Of or pertaining to preëmption; having power to preëmpt; preëmpting. 
[adj] - designed or having the power to deter or prevent an anticipated situation or occurrence
pre-emptive adjective designed or having the power to deter or prevent an anticipated situation or occurrence; `a preemptive business offer`
of or pertaining to preemption. · taken as a measure against something possible, anticipated, or feared; preventive; deterrent: a preemptive tactic against a ruthless business rival. · preempting or possessing the power to preempt; appropriative; privileged: a commander's preemptive authority. · pertaining to, involving, or not...