(physics) the average distance travelled between two similar events; especially by molecules in a gas or liquid, electrons or phonons in a crystal or neutrons in a moderator

(soccer) a free kick from which a goal may be scored only after the ball has been played by at least one other player

(soccer) a free kick from which a goal may be scored directly

(law, informal) the concept that a dog is not considered dangerous until it has bitten someone.

(algebra) a free module over the ring of integers

(algebra) A field of sets whose elements are equivalent to Boolean formulas (or, perhaps more precisely, equivalence classes of Boolean formulas). Starting with a set of n variables which are independent of each other and are called generators, the power set of this set has 2ⁿmembers which may be called atoms and are valuations of the n variables: a valuation can be considered to be a set of variables which are "true" under that valuation, or a conjunction of generators (such that variables not included in that set are included in negated form in the equivalent conjunction). Then the power set of the set of atoms yields a set of 2^(2ⁿ) members which are the elements of the said field of sets. These elements correspond to Boolean formulas: a formula can be considered to be a set of valuations which make the formula true, or a linear combination (i.e., a disjunction) of atoms.

plural of free imperial city

(historical) A self-ruling city within the Holy Roman Empire that had some autonomy and was represented in the Imperial Diet.

(historical) An unrecognized country that existed from 1863 to 1865, when Jones County, Covington County, Bainbridge County and portions of others, of the state of Mississippi, seceded from the Confederate States of America, and attempted to ally with the Union.

(biology, archaic) The formation of several cells from and in the protoplasm of the mother cell.