In the five paramitas, what is patience and why is it on the list? I understand the English dictionary definition of patience, the ability to wait.

When reading about the paramitas, it seems like this word in the original language covered forbearance, i.e. the ability to suffer other people's anger and insults calmly, in addition to the sense of be capable of waiting.

Was patience added to the list because of the huge time required to achieve full Buddhahood? Or is patience a sloppy translation and is this paramita really about forbearance?

Anyhow, in personal practice, if it means the ability to wait, then it isn't actionable since, patient or not, there is little risk of me reaching full Buddhahood on any given day.
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!