Sentence:  Gun set the captain 's <WSD>fifth</WSD> of Hiram Walker inside the safe before he reported to Lt. Killpath , though he knew that Killpath 's ulcer prevented him from making any untoward incursion on Herman Wolff 's gift . 
Meaning of the word marked with <WSD> tags:  a quantity of liquor equal to one fifth of a United States gallon