inconsistent
adj.adj. not staying the same or not following a clear pattern. You use this to describe someone who changes their behavior often or something that does not match other facts.
adj. lacking agreement, harmony, or a predictable pattern; displaying internal contradictions or varying in quality over time. Often modified by 'highly' or 'somewhat'.
His work is good but his attendance is inconsistent.
The witness gave an inconsistent account of the accident, changing several key details during the second interview.
The experimental results remained inconsistent across multiple trials, suggesting that an external variable was interfering with the chemical reaction in ways the team had not yet identified.
From in- + consistent.
Commonly followed by the preposition 'with' when comparing two things.
The results are inconsistent to the theoryThe results are inconsistent with the theoryInconsistent takes the preposition 'with', not 'to', when indicating a lack of agreement.