NAL (National Agricultural Library) Agricultural Thesaurus

AGROVOC Thesaurus (Food and Agriculture Organization of the United Nations)
"AGROVOC is a multilingual, structured and controlled vocabulary designed to cover the terminology of all subject fields in agriculture, forestry, fisheries, food and related domains" (Source: AGROVOC Thesaurus introduction page).

Getty Thesaurus of Geographic Names (TGN)

UNESCO (United Nations Educational, Scientific and Cultural Organization) Thesaurus