Real Dictionary

sub
countable noun: In team games such as football, a sub is a player who is brought into a match to replace another player.

sub in American English
abbreviation: supplemental unemployment benefits
intransitive verb: to act as a substitute for another
noun: a submarine
transitive verb: to coat (a film or plate) with a substratum

sub in American English 1
submarine
to be a substitute (for someone)

sub in American English 2
subaltern

sub in British English
abbreviation for: sport utility bike: a bicycle capable of carrying passengers or cargo
noun: short for several words beginning with sub-

sub-
prefix: Sub- is added to the beginning of nouns in order to form other nouns that refer to things that are part of a larger thing.
prefix: Sub- is used at the beginning of words that have 'under' as part of their meaning.

sub- in American English
under, beneath, below, from beneath
prefix: a prefix occurring originally in loanwords from Latin (subject; subtract; subvert; subsidy). On this model, sub- is freely attached to elements of any origin and used with the meaning “under,” “below,” “beneath” ( subalpine; substratum), “slightly,” “impe

sub- in British English
prefix: situated under or beneath

sub. in American English
abbreviation: subordinated

sub. in British English
abbreviation for: subeditor