Operationalizing your concepts, or determining synonyms, is important because different researchers may use different terminology to refer to the same things. You may find it useful to create a chart:

Common pitfalls when developing a search strategy:

You may realise that some concepts could use further brainstorming - and there may not always be exact synonyms for your concepts. Sometimes, using regular language can be helpful in addition to medical jargon, or using broader or more specific related keywords can help.

Some mistakes when identifying search terms can include not taking the time to fully define what a concept means to you (or your entire research team). Here are some common scenarios:

Trying to search for a condition or disease? Even if you start off with something like stress, you may need to define it further - there may be specific types to consider including:

• e.g. What you mean by "stress"? Does it include or exclude acute stress? Episodic? Chronic?

Searching for population-related characteristics, like a specific age group? What range of ages do you actually want to include?

• e.g. If you're searching for children, are you interested only in early childhood?  Or did you want to include adolescents or teenagers, or even young adults? 

Not finding enough relevant results?

• Sometimes in your concept table, you may end up identifying more than just 3 or 4 concepts. There's nothing wrong with this, but do consider that searching for all the concepts at once may be more restrictive than intended - sometimes try searching for your minimum searchable concepts, then just scan/screen the search results for your remaining concepts.
• Health databases often have limiters for certain types of concepts, so consider searching for these concepts till the end by using a limiter or a search filter - such as for age, geography, sex, or study type.

Continue operationalizing and refining until you have a a thorough list of terms to use in your database search.

Textword (or keyword) searching means using words you that could be found when searching the "record" of a database. The record DOES NOT include the full-text article. It mainly includes the TITLE, ABSTRACT, and (sometimes) AUTHOR-PROVIDED KEYWORDS. 

Subject heading searching means using preassigned words to search for articles labelled with that term. Each database uses its own subject headings - MEDLINE's are called MeSH (aka Medical Subject Headings). Subject headings are not the same in each database - for example, Embase's subject headings are called EMTREE headings.