what makes a move brilliant?

. . .

a move that your opponent, and most if not all of the onlookers, miss altogether. re: the game Byrne - Fischer, US Ch, 1963

A true brilliant move satisfies 4 criteria
It is a move that wins: moves that lose or draw are not brilliant.
It is the only move that wins: when several moves win, then none is brilliant.
It is a quiet move, no check or capture: those are too obvious.
It involves a sacrifice: sacrifices are aesthetically pleasing.

@tpr said in #3:

A true brilliant move satisfies 4 criteria
It is a move that wins: moves that lose or draw are not brilliant.
It is the only move that wins: when several moves win, then none is brilliant.
It is a quiet move, no check or capture: those are too obvious.
It involves a sacrifice: sacrifices are aesthetically pleasing.
Moves that draw in a losing position can be brillant

#4
By definition you cannot draw in a losing position.
Aside from that a move that draws lacks the lustre of a move that wins.

As far as I know, nobody has the authority to decide the meaning of “brilliant” for everyone. In terms of ECO code definitions, I believe that, strictly speaking, it is possible for Black to make a drawing move in a
+
-
position, but not possible for Black to make a drawing move in a +- position.

@fallboss007 why dont you quit citing whole posts for only one line within to refer to and that post is even r i g h t a b o v e !!??? O M G

@kindaspongey ' ± and +- ' are "ECO Code definitions" ???
inform yourself about the words you use

@tpr said in #5:

#4
By definition you cannot draw in a losing position.

Here is is: we have something we agree on. ;-)

If there is a drawing move, the position is not losing. It's really as easy as that.

Aside from that a move that draws lacks the lustre of a move that wins.

Not necessarily. There are quite a lot of really awesome drawing studies.

As brilliant moves are mathematically non-starters, I go with the more human approach: "non-obvious moves, that achieve an apparently unavailable goal", like winning or drawing a seemingly drawn or lost position. Usually, those moves would be hard to consider and have a surprise value. Bonus points for aesthetics. :-)

@nadjarostowa said in #8:

"non-obvious moves, that achieve an apparently unavailable goal", like winning or drawing a seemingly drawn or lost position

how about losing in a seemingly unlosable position? i can show some examples from my own games if you want to.

#8

• Brilliance is in the eye of the beholder.
  'There are no exclamation marks, as they serve no useful purpose. The best move should be mentioned in the analysis in any case; an exclamation mark can only serve to indicate the personal excitement of the commentator.[' - GM Robert Hübner

Here is an example:
https://www.chessgames.com/perl/chessgame?gid=1008361
The moves 11...Na4 and 17...Be6 qualify as brilliant as they satisfy all 4 criteria of #3.