Толковый словарь английского языка Oxford English Reference - constant

adj. & n. --adj. 1 continuous (needs constant attention). 2 occurring frequently (receive constant complaints). 3 (often foll. by to) unchanging, faithful, dependable. --n. 1 anything that does not vary. 2 Math. a component of a relationship between variables that does not change its value. 3 Physics a a number expressing a relation, property, etc., and remaining the same in all circumstances. b such a number that remains the same for a substance in the same conditions. Derivatives constantly adv. Etymology: ME f. OF f. L constare (as com-, stare stand)