'deforestation-promoting' is a compound of the noun 'deforestation' and the present-participial adjective 'promoting'. 'deforestation' itself was formed in English from 'deforest' + the nominalizing suffix '-ation' (see 'deforest'), and 'promoting' comes from the verb 'promote'.

'deforest' in English comes from Old French 'deforster' / 'desforester' (to remove trees from), with 'forest' ultimately from Medieval Latin 'foresta'. 'Promote' comes from Latin 'promovere' ('pro-' forward + 'movere' to move). The noun 'deforestation' arose later by adding '-ation' to 'deforest', and compounds like 'deforestation-promoting' are formed by combining the noun with 'promoting' to create a descriptive adjective.

Initially, 'deforest' and related forms referred specifically to the act of clearing trees. 'Promote' originally meant 'to move forward' or 'advance' and later 'encourage'. Combined, the compound now means 'encouraging or causing the clearing of forests', a specialized modern environmental usage.