Wiktionary
sub.
vb. 1 (abbreviation of substitute English) 2 (abbreviation of subaudi English)
Usage examples of "sub.".
He aimed at the lopsided superstructure of the sub. There was a crack and the answering bong of bullet against metal.
He led them through a corridor to an observation bay at the stern of the sub. Through a large porthole they could see the giant creature floating in the suction stream.
The man in the lead was whirled headlong into the holding chamber of the sub. The next man followed him, then the next, until every one had been snapped up by the vortex.