Suitable or fit to be relied on; worthy of dependance or reliance; trustworthy.

that which can be relied on; dependable; trustworthy; in testing, provides consistent results when administered on different occasions.

dependable, responsible, regularly does what it should do ...... back

worthy of reliance or trust; "a reliable source of information"; "a dependable worker"

how close repeated measures are to each other.

A reliable language test or other assessment tool produces the same results in the same group if the test is repeated, regardless of who is marking the test. A test can never be perfectly reliable but good tests strive for high reliability.

Statistical reliability refers to measurements that can be repeated with time. For example, a variable or statistic is said to be reliable if its value can be measured in the same way in repeated experiments.