Meaning

noun someone who is unimportant but cheeky and presumptuous

originFrom Middle English iack napys, iac nape, iac napes (“derogatory nickname of the English military commander and statesman William de la Pole, 1st Duke of Suffolk (1396–1450)”), probably from Jacun or Jakin (“pet forms of the male name Jack”) + ape (“ape, monkey”) + -s (possibly modelled after surnames such as Hobbes and Jakkes), referring to Suffolk’s heraldic badge which was an ape’s chain and…

Etymology from Wiktionary, CC BY-SA 3.0