Definition for Inquest :
a simple definition would be this;
an inquiry into the cause of an unexpected death
and... for not so simple definition....
wikipedia has this to offer...
An inquest is a judicial investigation, usually by a group of court-appointed people (jury), in common law jurisdictions. The most common kind of inquest is an inquiry including a medical examination by a coroner into the cause of a death that was sudden, violent, suspicious, or occurred in prison. Inquest can also mean such a jury and the result of such an investigation. In general usage, inquest is also used to mean any investigation or inquiry.
An inquest uses witnesses, but suspects are not permitted to defend themselves. The verdict can be, for example, natural death, accidental death, misadventure, suicide, or murder. If the verdict is murder or culpable accident, criminal prosecution may follow, and suspects are of course able to defend themselves there.