The phrase "mach ones" can be defined as the speed of sound, which is about 767 miles per hour at sea level. When looking for synonyms for this phrase, you can use words like "sonic speed," "sound barrier," and "supersonic." "Sonic speed" refers to the speed of sound, while "sound barrier" means the point at which an object reaches the speed of sound. "Supersonic" means faster than the speed of sound, which is commonly used in aviation and aerospace industries. Other synonyms for "mach ones" include "Mach speed," "Mach number," and "Mach rating." These terms are all used to describe the speed of an object compared to the speed of sound.