Other forms: furthering; furthered; furthers; furtherest; furtherer
If you ask your parents for money, they might say they need to think about it further and then ask you lots of questions. Further refers to figurative distance, like a thought you need more time on.
Further often gets confused with farther, but it's better to use further to mean an abstract distance, when two things are moving apart in terms of ideals, agreement, or thoughts, and farther when you're talking about physical distance. There's also a verb form of further that means "to promote the growth or progress of," which you might use in a sentence like, "These new gigs should help her further her career as a rock musician."