Mediate vs. Arbitrate
Meet vs. Meat
Melodious vs. Melodic
Memo vs. Memento
Memoranda vs. Memorandum
Missionary vs. Mercenary
Militate vs. Mitigate
Minimal vs. Nominal
Minimum vs. Minimal
Minister vs. Administer
Misogynist vs. Misanthropist
Misogamy vs. Misogyny
Missed vs. Mist
Mite vs. Might
Molten vs. Melted
Moment vs. Momentum
Momentous vs. Momentary
Monkish vs. Monastic
Monograph vs. Monogram
Monotonic vs. Monotonous