The Collaborative International Dictionary of English v.0.48:

Coroner \Cor"o*ner\ (k?r"?-n?r), n. [From OE. coronen to crown,
   OF. coroner, fr. L. coronare, fr. corona crown. Formed as a
   translation of LL. coronator coroner, fr. L. corona crown,
   the coroner having been originally a prosecuting officer of
   the crown. See Crown.]
   An officer of the peace whose principal duty is to inquire,
   with the help of a jury, into the cause of any violent,
   sudden or mysterious death, or death in prison, usually on
   sight of the body and at the place where the death occurred.
   [In England formerly also written and pronounced crowner.]
   [1913 Webster]

   Note: In some of the United States the office of coroner is
         abolished, that of medical examiner taking its place.
         [1913 Webster]

   Coroner's inquest. See under Inquest.
      [1913 Webster]

WordNet (r) 3.0 (2006):

coroner
    n 1: a public official who investigates by inquest any death not
         due to natural causes [syn: coroner, medical examiner]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "coroner":
   Doctor of Medicine, GP, MD, allopath, allopathist,
   attending physician, autopsy, country doctor, croaker, doc, doctor,
   family doctor, general practitioner, house physician, inquest,
   intern, leech, medical attendant, medical examiner, medical man,
   medical practitioner, medico, mortality committee, necropsy,
   necroscopy, physician, physician in ordinary, postmortem,
   postmortem examination, resident, resident physician, sawbones



Bouvier's Law Dictionary, Revised 6th Ed (1856):

CORONER. An officer whose principal duty it is to hold an inquisition, with
the assistance of a jury, over the body of any person who may have come to a
violent death, or who has died in prison. It is his duty also, in case of
the death of the sheriff, or when a vacancy happens in that office, to serve
all the writs and process which the sheriff is usually bound to serve. The
chief justice of the King's Bench is the sovereign or chief coroner of all
England, although it is not to be understood that he performs the active
duties of that office in any one count. 4 Rep. 57, b. Vide Bac. Ab. h.t.; 6
Vin. Ab.242; 3 Com. Dig. 242; 5 Com. Dig. 212; and the articles Death;
Inquisition.
     2. The duties of the coroner are of the greatest consequence to
society, both for the purpose of bringing to punishment murderers and other
offenders against the lives of the citizens, and of protecting innocent
persons from criminal accusations. His office, it is to be regretted, is
regarded with too much indifference. This officer should be properly
acquainted with the medical and legal knowledge so absolutely indispensable
in the faithful discharge of his office. It not unfrequently happens that
the public mind is deeply impressed with the guilt of the accused, and when
probably he is guilty, and yet the imperfections of the early examinations
leave no alternative to the jury but to acquit. It is proper in most cases
to procure the examination to be made by a physician, and in some cases, it
is his duty. 4 Car. & P. 571.