Widmer is from High Middle German, a word 'widemer' meaning: tenet farmer of Church Property.

Wikipedia Biographical Summary:

"...Peter Whitmer, Sr. (1773–1854) was an early member of the Latter Day Saint movement, and father of the movement's second founding family.

Peter Whitmer, Sr. was born April 14, 1773 in Pennsylvania and married Mary Elsa Musselman. The Whitmers had eight children together: Christian, Jacob, John, David, Catherine, Peter Jr., Nancy and Elizabeth Ann. In 1809, the family moved to Waterloo, New York, where they joined a German Reformed church and where Peter became a road overseer and school trustee. After 1827, they moved to Fayette.

In June 1829, Peter's sons and his son-in-law, Hiram Page, became witnesses to the Golden Plates and when the early Latter-day Saint church was organized on April 6, 1830, the Whitmers were among the first members. Their Fayette home is the traditional site of the church's organization. Oliver Cowdery, who had assisted Joseph Smith, Jr. in the translation of The Book of Mormon from the Golden Plates, married Elizabeth Ann Whitmer in December, 1832.

Peter and the entire Whitmer family broke with Latter Day Saint leader, Joseph Smith, Jr., in 1838 in Far West, Missouri. Peter moved to Richmond, Missouri where he lived until his death on August 12, 1854..."
SOURCE: http://en.wikipedia.org/wiki/Peter_Whitmer