GAR.
(abbreviation) Grand Army of the Republic, a fraternal organisation composed of veterans of the Union Army who had served in the American Civil War. The GAR was among the first organised advocacy groups in American politics and was succeeded by the Sons of Union Veterans of the Civil War (SUVCW). See http://en.wikipedia.org/wiki/Grand_Army_of_the_Republic
gdn.
(abbreviation) guardian.
GEDCOM:
(acronym) GEnealogy Data COMmunications. A standardised method of formatting family tree data as a text file, originally developed in 1985, which allows the exchange of data among different software programs and across operating systems. The GEDCOM specification is owned and managed by the Family History Department of the Church of Jesus Christ of Latter Day Saints.
good brother
(abbreviation) brother-in-law
good sister
(abbreviation) sister-in-law
good son
(abbreviation) son-in-law
grandam
(abbreviation) grandmother