The best way to find the name of that complicated mechanical part whose English translation you could only approximate: Google reverse image search

Here’s how to do it:

1. Do a regular Google image search for an image of the object whose name you want to translate in your source language. Example: Search for “gezahnte Unterlegscheibe”.
2. Right click one of the images which best shows your search object and choose “Copy image URL”.
3. Paste the URL into the file browser on the Reverse Image Search page. It will upload the image for searching.
4. Now Google will search for an English word that best describes your image. In this case: “serrated washer”!