Foremost
Definition 1 of 2
Pro Tip 1/3
Rank and Expertise
Use 'foremost' to describe a person as a leading expert in a field. He is the world's foremost authority on renewable energy.
Pro Tip 2/3
Superlative Use
'Foremost' is like a superlative; it means top-ranked or number one. The safety of our customers is our foremost concern.
Pro Tip 3/3
Not Always First
Even as the 'most important', 'foremost' doesn't always mean first in sequence. The foremost rule is respect, even if it's not the first one you learn.