ul·tra·mar·a·thon 
(ŭl′trə-mărə-thŏn′)
(ŭl′trə-mărə-thŏn′)n.
A cross-country footrace longer than a traditional marathon (26 miles, 385 yards).
ul′tra·mara·thon′er n.
- magneto-
- magnetoacoustics
- magnetoelectric
- magnetoelectricity
- magnetoencephalogram
- magnetoencephalographic
- magnetoencephalography
- magnetogram
- magnetograph
- magnetometer
- magnetometric
- magnetometry
- magnetomotive force
- magneton
- magnetooptics
- magnetopause
- magnetoresistance
- magnetoresistive
- magnetorheology
- magnetosphere
- magnetospheric
- magnetostriction
- magnetostrictive
- magnetotactic
- magnetotail