exact science

(sciences, strictly) A mathematical science, i.e. a field of science such as mathematics or mathematical physics which is capable of perfectly exact results based on rigorously formal methods.

(sciences, broadly) A field of science such as physics or chemistry that is not perfectly exact, but still capable of highly quantitative results based on methods that are are not strictly rigorous, but still systematic and scrupulous.

(litotes, chiefly in the negative) Used contrastively to characterize something as imprecise or relying on intuition or heuristics.