To subborn perjury means to entice, elicit, solicit, impel, whether by threat or promise, a false or misleading factual statement in or for a legal proceeding.
Perjury means: to swear a false oath, i.e. not merely lying or half truths, but also which are affirmed in some legal proceeding to be the truth.
Subbornation means to prompt, elicit, solicit, impel or compel, whether by threat or promise. See, e.g. 18 US Code Section 1622
Subornation of perjury can also constitute obstruction of justice (q.v.)