'belter' originates from Modern English as a derivative formed from the verb 'belt' plus the agentive suffix '-er' (i.e., 'one who belts' or something that 'belts'). 'Belt' (the root) goes back to Old English 'bælt'/'belt' meaning 'band' or 'strap', from Proto-Germanic roots relating to a band or strip.

'belt' existed as an Old English noun ('bælt'/'belt') meaning a band or strap; from this noun developed the verb 'to belt' (originally to hit with a belt or to fasten with a belt) and later senses such as 'to strike forcefully' and 'to sing forcefully'. The agentive formation with '-er' produced 'belter' in Modern English, which took on senses like 'one who belts', 'a strong blow', and the figurative 'an outstanding thing'.

Initially tied to the noun 'belt' (a strap) and the literal action of hitting with a belt, the related verb senses expanded to include strong striking and forceful vocalizing; over time 'belter' evolved to mean not only 'one who belts' but also 'a powerful blow' and figuratively 'an excellent or impressive thing' (especially for songs or performances).