'pro-gambling' originates from Modern English as a compound of the Latin prefix 'pro-' and the gerund 'gambling' (from the verb 'gamble'), where 'pro-' meant 'for' and 'gamble' meant 'to stake or play on an uncertain outcome.'

'gamble' developed in early 17th-century English (likely from notions of 'game' or influenced by words such as Middle English 'gamen' or 'gambol' meaning to play), and the modern compound 'pro-gambling' was later formed by attaching the prefix 'pro-' to 'gambling' to express support for it.

Initially the elements simply expressed 'for' + 'gambling' (i.e., supportive of gambling); the compound's meaning has remained focused on advocacy or favorable attitudes toward gambling but is now often used in political and regulatory contexts.