6 Ms

The traditional 6Ms are:

* Machines

* Methods

* Materials

* Measurements

* Mother Nature (Environment)

* Manpower (People)

Other definitions:

Machines
Methods
Materials
Measurements
Milieu (Mother Nature, surroundings, environment)
Manpower (People/mainly physical work)
Mindpower (Also people/mainly brain work)
Management (separate from Manpower/People because it considers Tampering)
Money
Miscellaneous
(the) Moon (so far unknown cause)

You can read more about it in the The Cause and Effect Diagram (a.k.a. Fishbone)
article.