55th is the ordinal form of the number 55. 55th or Fifty-fifth may also refer to:
A fraction, , equal to one of 55 equal parts
Geography 55th meridian east, a line of longitude 55th meridian west, a line of longitude 55th parallel north, a circle of latitude 55th parallel south, a circle of latitude 55th Street (disambiguation)
Military 55th Brigade (disambiguation) 55th Division (disambiguation) 55th Regiment (disambiguation)
Other 55th century 55th century BC
See also 55 (disambiguation)