S.Y.N.D.I.C.A.T.E or Syn.D - The organization which runs everything. Their HQ is located in Ophelia City, the Capital. 

Ophelia City - The capital city. Home to Syn.D HQ & known as Heaven On Earth.

Mythology Program - A program of operatives under Syn.D. A program which contents are classified & files stay with the founder, [REDACTED].

Syn.D Operatives - Are distinctly given numbered codenames. Only other Syn.D employees would know the true names of operatives.

N.I.G.H.T.M.A.R.E or The Council of Night - The organization that rivals S.Y.N.D.I.CA.T.E (Very much against the privilege Syn.D seem to have because they are an organization in the capital city, Ophelia City. Their HQ is located in Coral City, neighboring city outside the dome. 

Sync Test - The test used to qualify operatives into Syn.D.

Chemical G - a chemical that only has been said to be at Syn.D because it is a highly unstable