in·con·sis·tent 
(ĭn′kən-sĭstənt)
(ĭn′kən-sĭstənt)adj.
1. Displaying or marked by a lack of consistency, especially:
a. Not regular or predictable; erratic: inconsistent behavior.
b. Lacking in correct logical relation; contradictory: inconsistent statements.
c. Not in agreement or harmony; incompatible: an intersection inconsistent with the road map.
2. Mathematics Not solvable for the unknowns by the same set of values. Used of two or more equations or inequalities.
in′con·sistent·ly adv.