The Spanish word 'decisor' (meaning 'decision-maker') comes from the Spanish verb 'decidir' ('to decide') combined with the agent suffix '-or' (which indicates the person who performs an action). The verb 'decidir' itself comes from Latin 'decidere', which meant 'to cut off' or 'to decide'. This Latin word was formed by combining the prefix 'de-' (meaning 'down' or 'away') with the verb 'caedere' (meaning 'to cut'). The evolution from 'cutting off' to 'deciding' reflects how making a decision involves cutting away or eliminating other options.

Some related Spanish words that might be more familiar to Spanish learners include 'decidir' (to decide), 'decisión' (decision), and 'decidido' (decided, determined). All these words share the same Latin root 'decidere' and maintain the core concept of making choices or reaching conclusions.

English speakers can connect 'decisor' to several familiar English words that share the same Latin ancestry, such as 'decide', 'decision', 'decisive', and 'deciduous'. While most of these words relate to making choices, 'deciduous' (referring to trees that shed their leaves) maintains the original Latin meaning of 'cutting off' - in this case, the seasonal dropping of leaves.