You can use wildcards to search for variations in spelling and root words (along with their 'branches). Certain words are spelt different in British and American English, such as labor (labour in British spelling) and organization (organisation). Using a question mark (?) as a wildcard, you can find variations in spelling. Searching for organized labor, you might also search for organi$ed labo$r - this would search for variations in the spellings of both words.
Truncation is a type of wildcard searching and a fancy word for 'shortening' or searching by a stem/root word (think of the 'trunk' of a tree and the variations are the 'branches'). You can add an asterisk (*) at the end of the root or stem of the word.
For example, bio* may yield sources containing bioethics, biology, biotechnology, biodiversity, etc.
Be sure to identify the full root. If you're searching for variations of biotechnology you would search for biot* rather than bio*. Bio* would yield many results biological, biology, biologist, bioethics, and many more. In contrast, biot* would narrow the search to keywords like biotechnologist, biotechnological, and biotin. One additional letter in the stem can significantly narrow your results.
Truncation symbols may vary by database; common symbols include: *, !, ?, or #. The asterisk (*) is, by far, the most common truncation symbol.