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

Mate in 3. This happened in my game, I was looking for mate but couldn't find it and blundered. Yes, I'm terrible. : r/chess

Forced mate in one is forcedly preventable! : r/chess

Can I revert the move in chess, that is going back to same place again in the next move? If not, what is that term called? - Quora

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 does 'mate in one' mean in chess? Apparently, I've done it many times since my buddy keeps telling me it's my favorite checkmate move? - Quora

Watch Chess Pro Answers Questions From Twitter, Tech Support

M6 Puzzle for Mating Pattern Recognition : r/chess

This is a 1830 rated puzzle on lichess : r/chess

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

Check, Checkmate, & Stalemate Differences Explained (with GIFs)

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 is the definition of a mate in chess? - Quora

Check, Checkmate, & Stalemate Differences Explained (with GIFs)

How Is This Mate In 1? ♖ Tough Chess LOGIC Puzzle ♖ Chess Logic Puzzle