It is of a term again minted invented by them terrorist of the State Islamic. The term itself does not appear in older dictionaries, but the etymological root of the Word does exist in Arabic from very old, but not with the contextual meaning has taken in recent times because of its use by the terrorist organization.
Analysis etymological:????????????? : Is a name derived from a masdar of Form VII of the root (?).
As you have commented before, the meaning original of this root in Form VII (and also in the VIII) means quot; be submerged quot; or quot; living in the deep quot; of something. But the use of this term by the Islamic State, refers explicitly to a kind of quot; quot martyr; or Istishhadi, and who also dies while kill their enemies because of a conflict related to religion.
It should be clear, that not all them quot; martyrs quot; or quot; Istishhadiyin quot; they are quot; Inghimasiyin quot; as in islam moderately, a martyr or quot; Istishhadi quot; can be simply, a Muslim that dies because of declare your faith, without need of adopt an attitude aggressive against their executors (e.g., them Muslim shi'ies that are executed in regimes Sunni extremists, or of way analog to the Christianity, them martyrs of the first centuries that were executed simply by declare is Christian, as San Esteban).Unlike the term martyr quot; quot; in the context Christian of the early centuries, also are considered quot; Istishhadi quot; a Muslim who dies fighting with weapons in a war of autofdefensa, in a way more or less justified for political reasons, but without making the final act of suicide (for example, Muslims in the first centuries of the Hegira who died fighting against the tribe of the Quraysh, enemy of Muhammad, Qur'an 2:154).In this way, a quot; Inghimasi quot; would be exclusively, a kind of martyr quot; modern quot; (that has not existed in traditional islam), that dies making use of violence, and more specifically, committing suicide while he detonates an explosive device attached to his body (such as the explosive belts) causing the maximum possible damage to the target chosen against the attempt.
In the vocabulary West, can translate it perfectly by quot; kamikaze quot; but this translation is not acceptable to the terrorists of the Islamic State (and in fact, find it irritating that it translates this way), suicide (Intihar) is explicitly forbidden by the Islamic religion. In a way, that this terrorist organization uses the term quot; Inghimasi quot; as a euphemism to refer is to them kamikazes or terrorist suicide that die in attacks suicide against who they consider their enemies, in order justify his action without this between in apparent contradiction with the precept Islamic that prohibits the suicide.
Finally, note that the Act of making quot; Inghimas quot; it is considered a heresy for moderate islam, and results in a shameful act for the vast majority of Muslims who do not accept violence as a way that serve to justify the expansion of their religion.