further
(to a greater degree or level)
- I don’t want you to sink any further into debt.
- We will check further into the matter.
(more; additional)
- We have to wait for a further two days.
- We will arrange a further meeting.
UK (to a greater distance)
The road was closed, and we couldn’t go any further.
farther
(more distant)
- I decided not to go any farther.
- She lives farther up the road.