(mathematics, logic) such that the arguments or roles can be interchanged; "the arguments of the symmetric relation, `is a sister of,' are interchangeable"
not capable of being distinguished or differentiated; "the two specimens are actually different from each other but the differences are almost indistinguishable"; "the twins were indistinguishable"; "a colorless person quite indistinguishable from the colorless mass of humanity"
impossible or difficult to perceive by the mind or senses; "an imperceptible drop in temperature"; "an imperceptible nod"; "color is unperceivable to the touch"
not clearly defined or easy to perceive or understand; "indistinct shapes in the gloom"; "an indistinct memory"; "only indistinct notions of what to do"