What does 'mate in one' mean in chess? Apparently, I've done it

Mate in 5 I saw while watching a game between GMs (the GM didn't see, game in the first comment) : r/chess

New chess rule #chess #chesstok, chess edit

I was randomly playing against chess.com's top level bot and it made this blunder. No clue how. (Game link is in comments) : r/chessbeginners

What's the best check mate you've ever seen played in a game of chess? - Quora

How easy is mate in 1?

Bluff and thunder

I was losing so I let my opponent fork me on f6 in a desperate attent. Little did he know what has coming next : r/chess

What should be defined as an en passant checkmate? - Quora

How is this not a checkmate? Opponent ended up timing out, did the game client just glitch? : r/chessbeginners

Is there a position in chess where the only legal move is checkmate? - Quora