  Entropic Leggett-Garg inequality is studied in systems like neutrinos in the
context of two and three flavor neutrino oscillations and in neutral $B_d$,
$B_s$ and $K$ mesons. The neutrino dynamics is described with the matter effect
taken into consideration. For the decohering $B/K$ meson systems, the effect of
decoherence and CP violation have also been taken into account, using the
techniques of open quantum systems. Enhancement in the violation with increase
in the number of measurements has been found, in consistency with findings in
spin-$s$ systems. The effect of decoherence is found to bring the deficit
parameter $\mathcal{D}^{[n]}$ closer to its classical value zero, as expected.
The violation of entropic Leggett-Garg inequality lasts for a much longer time
in $K$ meson system than in $B_d$ and $B_s$ systems.
