The phrase 'countless countries' is correct and usable in written English.
It can be used to describe a large number of countries, particularly when the exact number is not known or not important. For example, "A vast network of roads exists in countless countries around the world."
Countless countries still seem doomed to autocracy without a homegrown version of its antidote.
Sewage is the largest marine pollutant on the planet, and damages the environment in countless countries.
American intelligence agencies do not work alone; we rely on strong ties to parallel organizations in countless countries.
There are worse curses to have, of course: compare Japan with the countless countries that have wrecked their economies by overexposing themselves to volatile international capital markets.
He and his wife Heather have travelled the world, from the North to the South Pole and all continents and countless countries in between.
"China has done little more than emulate a long pattern of U.S. manipulation, bribery and covert operations to influence the political trajectory of countless countries around the world," Mr. Kornbluh said.
Maybelle Carter's innovative playing style would eventually be imitated by countless country and folk guitarists.
Or, as Onslow suggests, Clandon could just be left, like countless country houses before it, as a beautiful wreck.
After last month's massacre in Las Vegas, 26 more people were killed in a shooting inside a church in Texas — the setting of countless country songs.
A lone telegraph pole, two skeletal trees and an outhouse complete a scene that could be the setting for countless country songs about growing up poor in hard times.
Even here in N.H.L. country, one did not have to explain to the offspring of immigrants from countless soccer countries how to enjoy a game.
