Taqiyya (alternate spellings taqiya, taqiyah, tuqyah)

(1.)Dissimulation - to conceal, partially conceal or disguise one's true feelings, beliefs or information when there is threat of death or serious harm and when there is a threat of great evil. Contrary to popular beliefs, this is not just a tenant of the Shia Islamic sect. All Muslims uphold it and it is logically and ethically necessary. It was practised by the Sahabah (RA), the companions of the Prophet Muhammed (SAW).
(2.)Taqiyya (alternate spellings taqiya, taqiyah, tuqyah) is a form of religious dissimulation,[1]or a legal dispensation whereby a believing individual can deny his faith or commit otherwise illegal or blasphemous acts while they are at risk of significant persecution.
(3.)"Concealing, precaution, guarding.” It is employed in disguising one's beliefs, intentions, convictions, ideas, feelings, opinions or strategies. In practical terms it is manifested as dissimulation, lying, deceiving, vexing and confounding with the intention of deflecting attention, foiling or pre-emptive blocking. It is currently employed in fending off and neutralising any criticism of Islam or Muslims.
* Just for the irony of it see Munafiq
Source 1 Islamic Dictonary
Source 2 Wikipedia
Source 3 Islam Watch