“___ 1 (speed of sound)” crossword clue

Reveal the answer to see why it works and where this clue has appeared before.MACH is the answer to the New York Times crossword clue “___ 1 (speed of sound)”. It was last seen in the puzzle of December 1, 2025, where it runs at 1 Down and fills 4 squares. It crosses 4 other entries in that grid — those are listed below and are the quickest way to confirm the letters you already have.