You can refer to a word or phrase as the keyword when you want to emphasize how important it is.
Collaboration was the keyword: editors, designers, picture researchers and productionstaff worked closely together.
...codes of conduct and ethical trading – the new keywords of the fair trade movement.
2. countable noun
A keyword is a word or phrase that is associated with a particular document or that describes the contents of a particular document,for example, in Internet searches.
Users therefore can search by title, by author, by subject, and often by keyword.
keyword in British English
(ˈkiːˌwɜːd)
noun
1.
a word used as a key to a code
2.
any significant word or phrase, esp a word used to describe the contents of a document
keyword in American English
(ˈkiˌwɜrd)
noun
a word or phrase submitted to a search engine in an effort to locate relevant documents or websites