Quote Originally Posted by Arixtotle View Post
"A raid is a type of mission in a video game in which a number of people attempt to defeat a boss monster or consecutive series of bosses."

"A more substantial engagement involving a large organized group of players typically set in a dungeon and involving difficult bosses."

Trials can certainly qualify as raids. Any content that involves more than the standard dungeon number of players, which is four in FFXIV of course, qualifies as a raid.
Except the game itself has classifications of what is a trial (the primals) and what is a raid (CT, coil). Your interpretation of what is a raid or not is pretty much moot if we're going by ingame terminology.