As an adjective:
* "The foremost expert on ancient civilizations was invited to give a lecture." (meaning the most important or leading expert)
* "Their foremost concern was the safety of their children." (meaning the most important or urgent concern)
As an adverb:
* "Foremost, I want to thank you for your support." (meaning most importantly or first of all)
* "The team played foremost in the competition, but unfortunately, they lost." (meaning they played with great skill and effort)
In a phrase:
* "Foremost among the challenges was finding enough funding." (meaning the most important challenge)
* "Foremost in her mind was the thought of her family." (meaning the most important thought)