Real Dictionary

Ministry of Defence in British English
noun: the government department responsible for the country's military measures or resources

mod
countable noun: Mods are young people in Britain who wear a special kind of neat clothes, ride motor scooters, and like soul music. Many young people were mods in the early 1960s.

Mod in American English
abbreviation: modal auxiliary

mod in American English 1
any of the young people in England in the mid-1960s noted for their emphasis on stylish dress, often as a symbol of their alienation from conventional society
of or characteristic of the mods or the styles they favored
adjective: very modern; up-to-date; being in the vanguard in style, dress, etc
noun: a person who is in the vanguard in style, dress, etc

mod in American English 2
moderate
noun: modification

MOD in British English
abbreviation for: Ministry of Defence

mod in British English 1
noun: a member of a group of teenagers in the mid-1960s, noted for their clothes-consciousness and opposition to the rockers

mod in British English 2
noun: an annual Highland Gaelic meeting with musical and literary competitions

mod in British English 3
abbreviation for: modulus

mod in British English 4
noun: a modification
verb: to modify (something)

mod in British English 5
noun: a moderator on an online forum
verb: to moderate (an online forum)

mod. in American English
abbreviation: moderate

mod. in British English
abbreviation for: moderate

modulus in British English 3
noun: a coefficient expressing a specified property of a specified substance