Not a dictionary as such, but I frequently use Wikipedia's "this article in another language" feature. The set of words for which a somewhat useful translation can be found like this, and words for which a translation can be found in dictionaries are almost completely disjoint.
As a concrete explanation, Wikipedia provides information on various specific terms that, if at all, would show up only in field-specific dictionaries:
- When I want to know the English translation of "Ameisenbär" (anteater), I check a dictionary, but when I want to know the English translation of "Büschelohrmaki" (hairy-eared dwarf lemur), I rather directly check whether Wikipedia has articles on the animal in both languages. (The Latin species names can usually be used to check whether both articles are indeed referring to the same animal.)
- Similarly, when I want to find the English translation of "Propeller" (propeller), I look it up in a dictionary, but for a more specific concept such as "Mantelpropeller" (ducted fan), or "Fenestron" ("fenestron" in English, too, but who knows?), I rather search on Wikipedia.