Sometimes you will need to look up words or get some background information before you are able to fully understand the articles you are reading in scientific journals. Here are some good online reference resources where you can find overview articles. These articles could be a good source of KEYWORDS which you will need to run accurate searches in journal databases.
And sometimes it's easiest to just use a good PRINT dictionary! Here are just two examples of fairly current psychology dictionaries found in McCabe's Reference section: