Dictionary:M(Mega)

{{#category_index:M|M}} 1. Mega-, SI prefix for 10⁶. 2. Roman symbol for 10³, as in MCF of gas. MM is used for 10⁶ in the petroleum industry. 3. The earthquake phase with the maximum amplitude on the seismogram, now obsolete. 4. The ratio of porosity determined from a sonic log to that from a density log.