mach
- n Austrian physicist and philosopher who introduced the Mach number and who founded logical positivism (1838-1916)
mach number
- n the ratio of the speed of a moving body to the speed of sound
machaeranthera bigelovii
- n wild aster having leafy stems and flower heads with narrow bright reddish-lavender or purple rays; western Colorado to Arizona
machaeranthera tanacetifolia
- n wild aster with fernlike leaves and flower heads with very narrow bright purple rays; Alberta to Texas and Mexico