A term used by US Navy personnel most often in the form of the acronym "nub" to describe new personnel aboard a submarine who have not yet qualified for submarines. Typically useless for anything other than cleaning, taking out the trash, and making fun of on watch.
Term is often mistaken by nubs to be synonymous with noob.
Keane: Non useful body... I don't know what's so offensive. Man, I called this one nub a nub and he's like "It's not 'nub,' it's 'noob.' I almost tased that little punk.
Finney: Why didn't you?
Keane: I didn't want to deal with all the taser acquisition forms.
Finney: What about... Currently Unqualified Naval Trainee?