insider

• POS: Noun
• HYPHEN: in=sid=er

CIDE DICTIONARY

insider, n. 

 an officer of a corporation or others who have access to private information about the corporation's operations, especially information relating to profitability.
"An insider is forbidden by U. S. securities laws to trade stock in publicly owned corporations based on the private information. The definition of insider for the purpose of securities law has changed in the late 29th century to become more inclusive, whereas it initially was applied only to officers of a corporation."  [WordNet 1.5]

OXFORD DICTIONARY

insider, n.
1 a person who is within a society, organization, etc. (cf. OUTSIDER).
2 a person privy to a secret, esp. when using it to gain advantage.

Idiom

insider dealing Stock Exch. the illegal practice of trading to one's own advantage through having access to confidential information.

THESAURUS

insider

Greek, affiliate, associate, belonger, brother, card-carrier, card-carrying member, cardholder, charter member, clubber, clubman, clubwoman, committeeman, comrade, confidential information, conventioneer, conventioner, conventionist, dues-paying member, enlistee, enrollee, fellow, fraternity man, guildsman, honorary member, initiate, inside dope, inside information, joiner, life member, member, one of us, pipeline, pledge, sister, socius, sorority girl, sorority woman, the lowdown