Nationwide
National, Countrywide
noun, の adjective
When something involves all the country you know it's nationwide or national.
ぜんこく
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
全国でインフルエンザがはやっています。
The flu is spreading nationwide.
リンゴのしゅうかくりょうが全国で一ばん多いけんはどこですか？
Which prefecture is the largest producer of apples nationwide?
彼は全国規模のサイバーいじめのスキャンダルに関与していた。
He was involved in a nationwide cyber bullying scandal.