Monotheism.
monotheis, the worship of only one god
Modernize is a word that starts with m and means to upgrade.
Make is a word that means to create and starts with "m".
The word MATE means one of a matched pair.
There could be multiple answers to this. RACISM is one such word starting with R and ending with M.
There are about a thousand Spanish words that start with m. Here are a few: Madre Malo Médico Mental Mientras Montaña Mujer
my
A four letter word that starts with J and ends with M: jism.
-Mad-Me
methionylglutaminylarginyltyrosylglutamylseryllleucylpheny
A muscle is a 7 letter word that starts with m and helps you run fast.
A seven (7) letter word that starts with M and ends with O: memento