The Tavern

The term "line of sight" is a newbie trap because it doesn't work at all how you would expect.

While "Light radius" isn't accurate either (since some areas of the dungeon are lit) it would do a much better job of conveying to the newer player than having less of it will make you harder to detect.

Perhaps even "detection range" or something similarly abstract/game-y?

Or just say "in sight" instead of "in LOS".

but that's not always true either, when things are behind glass they can't be targeted by things like Smite despite being in sight.

I would say in terms of game mechanics there are three distinctions made "visible" (inside your vision range, with no nontranslucent walls in the way), "unobstructedly visible" and "unobstructedly visible with no other creatures in between"

Historically, we have used line-of-sight (LOS) to refer to the second category, and line-of-fire (LOF) to refer to the third.

What's an actual example of a place in-game that uses "line of sight" when referring to LOS_RADIUS? As far as I'm aware it's pretty consistently referred to as "vision range" or words to that effect, which seems fine (see the descriptions for Darkness and the robe of Night).

"Line of sight" is used accurately in a few places (statues are described as "interrupts your line of fire, even though it doesn't interrupt your line of sight").