The Spanish word 'plural' comes from the Latin word 'pluralis', meaning 'relating to many'. This Latin word was formed by combining two elements: 'plus' meaning 'more' and the suffix '-alis' meaning 'relating to'. So literally, 'pluralis' meant 'relating to more (things)'.

The Spanish word 'plus' (meaning 'plus' or 'additional') shares the same Latin root 'plus'. Similarly, words like 'pluralidad' (plurality) and 'pluralismo' (pluralism) are derived from the same base.

The English word 'plural' is a direct cognate of the Spanish word, both coming from Latin 'pluralis'. Other related English words include 'plus', 'plurality', and 'pluralism'. The mathematical symbol '+' is called a 'plus sign' because it indicates addition or 'more', reflecting the original Latin meaning.