sub

UK: /ˈsʌb/ US: /sʌb/ ,(sub)

Inflections of 'sub' (v): (⇒ conjugate)

subs

v 3rd person singular

subbing

v pres p

subbed

v past

subbed

v past p

WordReference Random House Learner's Dictionary of American English © 2025

sub /sʌb/   n., v., subbed, sub•bing. 
n. [countable]

1. Informal Terms a submarine.
2. a substitute:
   We hired a sub to teach her class.
3. Food, Dialect Terms a submarine sandwich.

v. [no object]

4. Informal Terms to act as a substitute for another:
   Can you sub for their French teacher tomorrow?

sub-, prefix. 

1. • sub- comes from Latin, where it has the meaning "under, below, beneath'':
     subsoil; subway.
   • sub- is also used to mean "just outside of, near'':
     subalpine; subtropical.
   • sub- is also used to mean "less than, not quite'':
     subhuman; subteen.
   • sub- is also used to mean "secondary, at a lower point in a hierarchy'':
     subcommittee; subplot.

Sometimes this prefix is spelled as su-, suc-, suf-, sug-, sum-, sup-, sur-², sus-.
sub.,  an abbreviation of:

1. Military substitute.
2. suburb.
3. suburban.
4. Transport subway.

WordReference Random House Unabridged Dictionary of American English © 2025

sub (sub),  n., v., subbed, sub•bing. [Informal.]

n. 

1. Informal Terms a submarine.
2. a substitute.
3. Food, Dialect Terms, Dialect Terms a submarine sandwich. See hero sandwich. 
4. Informal Terms a subcontractor.
5. a sublieutenant.
6. Informal Terms a subordinate.
7. a subaltern.
8. British Terms an advance against one's wages, esp. one granted as a subsistence allowance.
9. Informal Terms, Photography [Photog.] a substratum.

v.i. 

10. Informal Terms to act as a substitute for another.

v.t. 

11. Informal Terms, Photography [Photog.] to coat (a film or plate) with a substratum.

• by shortening of words prefixed with sub-

Regional Variation

3. See hero sandwich. 

SUB, 

1. Business, Government supplemental unemployment benefits.

sub-, 

1. a prefix occurring originally in loanwords from Latin (subject;
   subtract;
   subvert;
   subsidy);
   on this model, freely attached to elements of any origin and used with the meaning "under,'' "below,'' "beneath'' (subalpine;
   substratum), "slightly,'' "imperfectly,'' "nearly'' (subcolumnar;
   subtropical), "secondary,'' "subordinate'' (subcommittee;
   subplot).
2. Chemistry
   • Chemistry a prefix indicating a basic compound:
     subacetate;
     subcarbonate;
     subnitrate.
   • Chemistry a prefix indicating that the element is present in a relatively small proportion, i.e., in a low oxidation state:
     subchloride; suboxide.
Also, su-, suc-, suf-, sug-, sum-, sup-, sur-, sus-. 
• Latin, combining form representing sub (preposition); akin to Greek hypó; see hypo-

sub., 

1. subordinated.
2. Journalism subscription.
3. Military substitute.
4. suburb.
5. suburban.
6. Transport subway.

Collins Concise English Dictionary © HarperCollins Publishers::

sub / sʌb/ noun

1. short for several words beginning with sub-
   See subaltern, subeditor, submarine, subordinate, subscription, substandard, substitute
2. an advance payment of wages or salary
   Formal term: subsistence allowance

verb (subs, subbing, subbed)

1. (intransitive) to serve as a substitute
2. (intransitive) to act as a substitute (for)
3. to grant or receive (an advance payment of wages or salary)
4. (transitive)
   short for subedit

Collins Concise English Dictionary © HarperCollins Publishers::

sub- prefix

1. situated under or beneath: subterranean
2. secondary in rank; subordinate: subeditor
3. falling short of; less than or imperfectly: subarctic, subhuman
4. forming a subdivision or subordinate part of a whole: subcommittee
5. (in chemistry) indicating that a compound contains a relatively small proportion of a specified element: suboxide
6. indicating that a salt is basic salt: subacetate

Etymology: from Latin sub

Collins Concise English Dictionary © HarperCollins Publishers::

sub. abbreviation

1. subeditor
2. subito (in music)
3. subscription
4. substitute