WordWeight : Weighing the Words

Pronunciation : Fi"at
Part of Speech : n.
Etymology : [L., let it be done, 3d pers. sing., subj. pres., fr. fieri, used as pass. of facere to make. Cf. Be.]
Definition : 1. An authoritative command or order to do something; an effectual decree. His fiat laid the corner stone. Willis.

2. (Eng. Law) (a) A warrant of a judge for certain processes. (b) An authority for certain proceedings given by the Lord Chancellor's signature. Fiat money, irredeemable paper currency, not resting on a specie basis, but deriving its purchasing power from the declaratory fiat of the government issuing it.
Source : Webster's Unabridged Dictionary, 1913