from
The Collaborative International Dictionary of English v.0.48
constantan \constantan\ n.
a copper-nickel alloy composed of approximately 55 per cent
copper and 45 per cent nickel, with high electrical
resistance and a low temperature coefficient; it is used as
resistance wire and in thermocouples.
Note: It has a resistance factor [rho] of 44.1 x 10^{-6}
ohm-cm at 0[deg] C, in comparison to the value 1.71 x
10^{-6} ohm-cm for pure copper and 7.8 x 10^{-6} ohm-cm
for pure nickel. It is similar to the alloy Eureka,
which has a [rho] = 47 x 10^{-6} ohm-cm. --Handbook of
Ch. 61.
[WordNet 1.5 +PJC]