insider

inside +‎ -er

• (General American) IPA^(key): /ɪnˈsaɪdɚ/, /ˈɪnsaɪdɚ/
  • Homophone: inciter
• Rhymes: -aɪdə(ɹ)

insider (plural insiders)

1. A person who has special knowledge about the inner workings of a group, organization, or institution.
   • 1923, "‘Big Board’ Failures," Time, 2 Jul.,

     Heavy losses were sustained in Simms Petroleum, which took a greater toll from supposed "Wall Street insiders" than from the general public.

   • 2007, Jonathan Clayton, "Profile: Zuma charmed wives and a nation," Times of London (UK), 19 Dec.,

     He is also an astute ANC insider who spent ten years on Robben Island alongside Nelson Mandela and the other “grandees” of the movement.

   • 2018 July 31, Julia Carrie Wong, “What is QAnon? Explaining the bizarre rightwing conspiracy theory”, in The Guardian‎:

     In a thread called “Calm Before the Storm”, and in subsequent posts, Q established his legend as a government insider with top security clearance who knew the truth about a secret struggle for power involving Donald Trump, the “deep state”, Robert Mueller, the Clintons, pedophile rings, and other stuff.

2. A person who is within an enclosed space.
   • 1849, Herman Melville, Redburn: His First Voyage, ch. 33,

     To the insider, the ceiling is like a small firmament twinkling with astral radiations.

• insider trading

• German: Insider
• Japanese: インサイダー (insaidā)

• irenids, neriids, sirenid