The word Yponomeutoidea comes from the Ancient Greekὑπό (ypo) meaning under and νομός (nomós) meaning food or dwelling, thus "feeding secretly, or burrow".
Sources
Firefly Encyclopedia of Insects and Spiders, edited by Christopher O'Toole, ISBN 1-55297-612-2, 2002
van Nieukirken et al., 2011. Order Lepidoptera Linnaeus, 1758. In:Zhang, Z.-Q. (ed.) Animal Biodiversity: an outline of higher-level classification and survey of taxonomic richness. Zootaxa3148: 212-221.