The Spanish word 'sino' has two distinct etymological origins and meanings. In its first sense meaning 'fate' or 'destiny', it comes from the Latin word 'signum' meaning 'sign, signal, or omen'. This semantic evolution from 'sign' to 'fate' makes sense as omens and signs were historically used to divine one's destiny.

In its second sense as a conjunction meaning 'but rather', 'sino' is actually a compound word formed from the combination of Spanish 'si' ('if, yes') and 'no'. This combination created a contrastive conjunction used to introduce an alternative or correction to a negative statement.

The Spanish words 'si' ('if, yes') and 'no' are simpler and more fundamental vocabulary words that combine to form 'sino' in its conjunctive sense. Additionally, the word 'seña' ('sign') and 'señal' ('signal') are related to the 'fate/destiny' sense of 'sino' as they also derive from Latin 'signum'.

English words related to the 'fate/destiny' sense of 'sino' include 'sign', 'signal', and 'signature', all of which come from the same Latin root 'signum'. You can see how these English words maintained meanings closer to the original Latin sense of a mark or indicator, while the Spanish 'sino' developed a more specific meaning related to fate.