Measurement of the concentration or potency of a substance by its effect on living cells or tissue; a particular test of this kind; = biological assay…

Esp. in biological assay (= bioassay, n.), the determination of the strength of a substance by means of a test on an organism, usually in comparison…

measurement of the concentration, potency, or other properties of a substance by its qualitative or quantitative effect on living cells or organisms.

the use of antibodies for the detection of and measurement of biochemical substances; any of various techniques involving this; cf. radioimmunoassay…