first class (the most luxurious and expensive class of accommodation on a train, airplane, etc.)

female equivalent of premier-né: female firstborn

First World War

at first sight, at first blush, at first glance, at a glance

front cover, front page, title page

straight from the horse's mouth, firsthand, directly from the source

essential

headfirst, headlong

(figuratively) to lay the first stone, to lay the foundation stone

early, who was there right from the start, who has joined from the very beginning