到底

dàodǐ
  1. finally
  2. in the end
  3. when all is said and done
  4. after all
  5. to the end
  6. to the last

CEDICT

Entry Composition

1 到 dào
  1. to reach; to arrive
  2. to leave for; to go to
  3. to (a place); until (a time); up to (a point)
  4. (verb complement indicating arriving at a place or reaching a point)
  5. considerate; thoughtful; thorough
2 底 dǐ
  1. bottom; base
  2. background; foundation
  3. copy (of a manuscript or receipt etc) kept as a record
  4. (suffix) end of a year or month
  5. (math.) radix; base (abbr. for 底数 dǐshù)