'even-toothed' originates from a combination of English elements: 'even' (from Old English 'efen' via Middle English 'even'), where 'efen' meant 'level, equal', and 'toothed' formed from 'tooth' (Old English 'tōþ'), where 'tōþ' meant 'tooth'.

'even-toothed' was formed in Modern English by compounding the adjective 'even' with the past-participle/adjectival form 'toothed' (from Old English 'tōþ' > Middle English 'tooth'); the compound pattern follows productive English compounding of descriptive elements.

Initially, the elements meant 'level/equal' (even) and 'tooth' (tooth); over time the compound came to be used descriptively to mean 'having teeth equal in size or spacing'.