When Alexander Thom was born on 24 June 1798, in Culsalmond, Aberdeenshire, Scotland, his father, John Thom, was 27 and his mother, Margaret Robb, was 25. He married Isabel Leslie on 13 December 1823, in Old Aberdeen, Aberdeen, Aberdeenshire, Scotland, United Kingdom. They were the parents of at least 1 daughter. He lived in Old Aberdeen, Aberdeen, Aberdeenshire, Scotland, United Kingdom in 1841 and Aberdeen, Aberdeenshire, Scotland, United Kingdom in 1851.
Scottish and English: from the Middle English personal name T(h)om(me), a pet form of Thomas . In Scotland, Thom is also an Anglicized form of Gaelic Mac Thom, see McComb .
German: from the personal name Thom, a pet form of Thomas . This surname is also found in France.
Chinese: variant Romanization of the surname 譚, see Tan 1.