Jill
来自Big Physics
late Middle English: abbreviation of the given name Gillian .
wiktionary
By analogy with jack (off). See Jack(“male name”) and Jill(“female name”).
From the female name Jill.
From the female name Jill; paired with jack (from the male name Jack) as terms for alcohol measurements.
etymonline
Jill
fem. proper name, Middle English Jille, Jylle, Gille, etc., familiar shortening of Jillian, Gillian, which represent the common Middle English pronunciation of Juliana (see Gillian). A very popular name for girls in medieval England, hence its use as a familiar, almost generic, name for a girl (early 15c.; paired with Jack since mid-15c.).
