fi·at 
(fēət, -ăt′, -ät′, fīăt′, -ət)
(fēət, -ăt′, -ät′, fīăt′, -ət)n.
1. An arbitrary order or decree.
2. Authorization or sanction: government fiat.
[Medieval Latin, from Latin, let it be done, third person sing. present subjunctive of fierī, to become, to be done; see bheuə- in the Appendix of Indo-European roots.]