We always need to find definitions for terms we encounter in our translations. One way to do so is to enter our search term in quotes, and add the word "definition" before launching our search in Google (or other search engine). This is a good technique that usually helps to find more formal definitions, for example from certain on-line dictionaries (as well as from other sources). Adding the word "definition" to a search, however, is not the only option to help you find the definition of some term.
A often useful way to find hidden definitions is to search for a specific pattern such as "a [your search term] is a" as a complete string, for example "an hydraulic pump is a". The results found by such searches often come from the body of documents, instead of dictionary entries, and sometimes are even more useful to help you understand what your term means than regular dictionary definitions.
Similar pattern searches can also help: for example "a [your search term] is used for", "the purpose of [your search term] is", and so on. You can refine such searches by, for example, limit them to a specific domain, or perhaps to a specific region. Your results may vary depending on the search engine you use.
This technique can be adapted to most languages, for example "Un [your search term] es un" in Spanish, or "Una [your search term] è una" in Italian.