1) Economic expert 2) Economic theory 3) Economist 
• (a.) Of or pertaining to the political economist, the Rev. T. R. Malthus, or conforming to his views; as, Malthusian theories.
Mal·thu'sian adjective Of or pertaining to the political economist, the Rev. T. R. Malthus , or conforming to his views; as, Malthusian theories. » Malthus held that population tends to increase faster than its means of subsistence can be made to do, and hence that the lower classes...
[adj] - of or relating to Thomas Malthus or to Malthusianism 2. [n] - a believer in Malthusian theory
adjective of or relating to Thomas Malthus or to Malthusianism; `Malthusian theories`