Noun
Agent noun of preload; one who, or that which, preloads.
(web development, historical) In Flash animations, the loading screen that stalls for time while resources are downloaded.
Source: en.wiktionary.orgHowever, with the browser’s preloader, only resources which are declared in the HTML document are preloaded. Source: Internet
And so especially for the top level component, it's very common to actually put the, really a preloader right in there in the middle. Source: Internet