The Spanish word 'ecuador' comes from the Latin word 'aequator', meaning 'equalizer'. This Latin term was formed by combining the verb 'aequare' (meaning 'to make equal'), which itself comes from 'aequus' (meaning 'equal'), with the agent suffix '-tor'. The term was used to refer to the equator because it divides the Earth into two equal parts - the Northern and Southern hemispheres.

Some related Spanish words include 'igual' (equal), 'igualar' (to make equal), and 'ecuación' (equation). While these words took slightly different paths from Latin to Spanish, they all share the basic concept of equality or making things equal.

In English, we can find several related words that share the same Latin root 'aequus'. The most obvious is 'equator' itself, which is nearly identical to the Spanish 'ecuador'. Other related English words include 'equal', 'equation', 'equalize', and 'equity'. All these words maintain the core meaning of fairness, equality, or balance that was present in the original Latin.