Bloom has several culinary meanings. Blooming spices means briefly warming them in fat or liquid to release and distribute flavor; tempering spices is a related preparation in which flavored fat seasons a dish. Spices burn easily, so use the recipe's method and signs of readiness.
Blooming gelatin means hydrating it in cool liquid before dissolving it. Bloom strength is a measurement of gelatin firmness, not that hydration step. On chocolate, bloom describes a pale surface coating associated with changes in fat or sugar; the word does not describe one universal process.
Reference: Further reading.