The Spanish word 'argumental' (meaning 'argumentative' or 'relating to an argument') comes from combining the Spanish word 'argumento' ('argument') with the suffix '-al' (meaning 'relating to'). The word 'argumento' itself comes from Latin 'argumentum' meaning 'argument' or 'proof', which was formed from the Latin verb 'arguere' ('to make clear') and the suffix '-mentum' (indicating an instrument or result).

This etymology shows how the word was built up in layers: first combining 'arguere' with '-mentum' to create a noun for the result of making something clear (an argument or proof), then this word passing into Spanish as 'argumento', and finally adding '-al' to create an adjective describing things related to arguments.

A simpler and more common related Spanish word is 'argumento' (argument), which is the base word from which 'argumental' is derived. Another related word is 'argumentar' (to argue), which is the verbal form. These words share the core meaning of presenting clear reasoning or proof.

Several common English words are related to 'argumental' through the shared Latin root 'arguere'. These include 'argue', 'argument', and 'argumentation'. The English word 'argument' is particularly close, coming from the same Latin word 'argumentum' as the Spanish 'argumento'. Even the English suffix '-al' (as in 'argumental') shares the same Latin origin as the Spanish '-al', though this form is less common in English than 'argumentative'.