Merriam-Webster's Collegiate Dictionary:
materialistically
materiality
materialization
materialize
materializer
materially
materialness
materials science
materials scientist
materiel
maternal
maternally
maternity
matey
mateyness
math
mathematic
mathematical
mathematical expectation
mathematical induction
mathematical logic
mathematically
mathematician
mathematics
mathematization
mathematize
mather
maths
mathura
matin
matin?e
matinal
matinee
matinee idol
matins
matisse
matlock
mato grosso
mato grosso do sul
mato tepee
matr-
matri-
matriarch
matriarchal
matriarchate
matriarchy
matricidal
matricide
matriculant
matriculate
matriculation
matrilineal
matrilineally
matrimonial
matrimonially
matrimony
matrimony vine
matrix
matro-
matron
matron of honor
matronly
matronymic
matruh
matsu
matsudo
matsuo
matsuoka
matsushima
matsutake
matsuyama
matsys
matt
mattagami
mattaponi
matte
matteotti
matter
matter of course
matter-of-fact
matter-of-factly
matter-of-factness
matterhorn
mattery
matthaean
matthean
matthew
matthews
matting
mattins
matto grosso
mattock
mattress
matur?n
maturate
maturation
maturational
