the.com/fifth

means The one after fourth — an ordinal number, and also a standard liquor bottle holding roughly 750ml, originally a fifth of a gallon.

from Old English 'fifta,' built from 'fif' (five) plus the ordinal-forming suffix, a straightforward Germanic pattern you still see in 'sixth' and 'tenth.' The liquor sense is the fun twist: 19th-century American spirits were commonly sold in bottles sized at one-fifth of a gallon, and the fraction simply took over as the bottle's name. The word stayed put while the gallon quietly dropped out of the conversation.