Definition of "sub"
sub1
/sʌb/
noun
plural subs
(nautical) A submersible
(colloquial) A subcontractor.
(publishing, colloquial) A submission (of a work for publication).
(BDSM, informal) A submissive.
(colloquial, dated) A subordinate.
verb
third-person singular simple present subs, present participle subbing, simple past and past participle subbed
(US, informal) To substitute for.
(BDSM) To take a submissive role.
sub2
/sʌb/
preposition
verb
third-person singular simple present subs, present participle subbing, simple past and past participle subbed