Quenched disorder simply means that the disorder is explicitly present in the Hamiltonian, typically under the form of random couplings J among the degrees of freedom. For instance, if we consider the famous Edwards-Anderson model $$ H = -\sum_{\langle i, j \rangle} J_{ij} \sigma_i \sigma_j,$$ the disorder is quenched, meaning that the $J$ are constant on the time scale over which the $\sigma$ fluctuate.

For a nice discussion on quenched disorder, which occurs for spin glasses, (and its distinction from annealed disorder), refer to the paper Spin-Glass Theory for Pedestrians by Tommaso Castellani, and Andrea Cavagna.

Quenched disorder simply means that the disorder is explicitly present in the Hamiltonian, typically under the form of random couplings among the degrees of freedom. For instance, if we consider the famous Edwards-Anderson model $$ H = -\sum_{\langle i, j \rangle} J_{ij} \sigma_i \sigma_j,$$ where $J_{ij}$ are random variables drawn from some probability distribution, the disorder is indeed quenched, meaning that the $J$ are constant on the time scale over which the $\sigma$ fluctuate.

For a nice discussion on quenched disorder (which is the case of relevance for spin glasses) and its distinction from annealed disorder, I would recommend taking a look at Sec. 2 of the paper Spin-Glass Theory for Pedestrians by Tommaso Castellani, and Andrea Cavagna.