到底

finally / in the end / when all is said and done / after all / to the end / to the last

to (a place) / until (a time) / up to / to go / to arrive / (verb complement denoting completion or result of an action)

to reach; to arrive / to leave for; to go to / to (a place); until (a time); up to (a point) / (verb complement indicating arriving at a place or reaching a point) / considerate; thoughtful; thorough

(equivalent to 的 as possessive particle)

background / bottom / base / end (of the month, year etc) / remnants / (math.) radix / base

in the final analysis / in the end

after all / in the final analysis / ultimately

to brave it out / to the bitter end

to argue endlessly / to try to have the last word

to go to the bottom of things (idiom)