The Spanish word 'descansado' (meaning 'rested') comes from the verb 'descansar' ('to rest'), which is formed by combining the prefix 'des-' (indicating reversal or negation) with the verb 'cansar' ('to tire'). The verb 'cansar' can be traced back to the Latin word 'campsare' meaning 'to turn or bend', which itself derives from the Ancient Greek 'κάμπτειν' (kamptein) meaning 'to bend'. The past participle suffix '-ado' is added to form 'descansado'.

The semantic evolution is quite interesting - from the original meaning of 'bending' in Greek, the concept evolved to mean 'tiring' in Spanish (perhaps from the idea of being bent over from exhaustion), and then with the addition of the reversal prefix 'des-', it came to mean 'removing tiredness' or 'resting'.

A simpler and more common related Spanish word is 'cansar' meaning 'to tire' or 'to fatigue'. You might hear 'estoy cansado' meaning 'I am tired'. Understanding this connection can help you remember that 'descansado' essentially means 'un-tired' or 'rested'.

While there aren't many common English words directly related to 'descansado', you might encounter some technical terms that share the Greek root 'kampt-'. For example, 'campsis' in biology refers to the bending of plant organs in response to stimuli. The connection between bending and tiredness in the Spanish evolution of meaning is unique to the Romance languages.