ˈ ̷ ̷ˈtäm(p)sən- noun
Usage: usually capitalized J&T
Etymology: after J. P. Joule and Sir William Thomson (Lord Kelvin) died 1907 British physicist
: the change in temperature of a gas on expansion through a porous plug from a high pressure to a lower one under adiabatic conditions, the observation of this change proving among other things that Joule's second law is only approximately true