[1] : WordNet (r) 2.0

tour of duty
     n : a period of time spent in military service syn: enlistment,
          hitch, term of enlistment, duty tour, tour
see also:
enlistment hitch term of enlistment duty tour tour 

[2] : Moby Thesaurus II by Grady Ward, 1.0

25 moby thesaurus words for "tour of duty":
   anchor watch, bit, day shift, dogwatch, full time, graveyard shift,
   half time, lobster trick, night shift, overtime, part time, relay,
   shift, split schedule, split shift, stint, sunrise watch,
   swing shift, time, tour, trick, turn, turn of work, watch,
   work shift

Duty >> D Words
Duty, definition of term: Duty
duty_pag1.html

Tour >> T Words
Tour, definition of term: Tour
tour_pag1.html

Fiduciary Duty >> F Words
Fiduciary Duty, definition of term: Fiduciary Duty
fiduciary+duty_pag1.html

Off Duty >> O Words
Off Duty, definition of term: Off Duty
off+duty_pag1.html

Fatigue Duty >> F Words
Fatigue Duty, definition of term: Fatigue Duty
fatigue+duty_pag1.html

Civic Duty >> C Words
Civic Duty, definition of term: Civic Duty
civic+duty_pag1.html

Customs Duty >> C Words
Customs Duty, definition of term: Customs Duty
customs+duty_pag1.html

Tour De Force >> T Words
Tour De Force, definition of term: Tour De Force
tour+de+force_pag1.html

Breach Of Duty >> B Words
Breach Of Duty, definition of term: Breach Of Duty
breach+of+duty_pag1.html