Definition of jackshay in English:

jackshay

(also Jack Shay, Jack Shea)

Pronunciation /ˈdʒakʃeɪ/

noun

historical, rare Australian
  • A quart pot used for brewing tea and incorporating a smaller vessel for drinking.

Origin

Mid 19th century; earliest use found in Sydney Mail. Perhaps from the male forename Jack + the surname Shea, as rhyming slang for tea.