In the five paramitas, what is patience and why is it on the list?
Patience is actually a great translation.  Think of the etymology of the English word:


  patience (n.) - c. 1200, "quality of being willing to bear
  adversities, calm endurance of misfortune, suffering, etc.," from Old
  French pacience "patience; sufferance, permission" (12c.) and directly
  from Latin patientia "patience, endurance, submission"


Patience is to suffer the slings and arrows of outrageous fortune.  It is to endure, without complaint.  When one is patient, they turn headlong into discomfort and do so with a mind marked by equanimity.  Think of the countless lives of the Buddha - all of the suffering he had to endure in order to achieve nirvana.  His was a patience par excellence.

Patience is an indispensable virtue on the road to Buddhahood and absolutely deserves to be on this list!