a (1): to compute the difference between the debits and credits of (an account) (2): to pay the amount due on :settle
b (1): to arrange so that one set of elements exactly equals another <balance a mathematical equation>(2): to complete (a chemical equation) so that the same number of atoms and electric charges of each kind appears on each side
a: the relation in physiology between the intake of a particular nutrient and its excretion—used with positive when the nutrient is in excess of the bodily metabolic requirement and with negative when dietary inadequacy and withdrawal of bodily reserves is present; see nitrogen balance, water balanceb: the maintenance (as in laboratory cultures) of a population at about the same condition and level
Instrument for comparing the weights of two bodies, usually for scientific purposes, to determine the difference in mass. The equal-arm balance dates back to the ancient Egyptians, possibly as early as 5000 BC. By the early 20th century, it had been developed into an exquisitely precise measuring device. Electronic balances today depend on electrical compensation rather than mechanical deflection. The ultramicrobalance is any weighing device that serves to determine the weight of even smaller samples than can be weighed with the microbalance (which can weigh samples as small as a few milligrams), that is, total amounts as small as a few micrograms.