The Spanish adverb 'relajadamente' (meaning 'relaxedly' or 'in a relaxed manner') comes from combining the adjective 'relajado' ('relaxed') with the adverbial suffix '-mente'. This suffix comes from the Latin word 'mens, mentis' meaning 'mind', and is used to form adverbs in Spanish similar to how '-ly' works in English.

Going further back, 'relajado' comes from the verb 'relajar' ('to relax'), which derives from Latin 'relaxare'. The Latin word was formed by combining the intensive prefix 're-' with the verb 'laxare' meaning 'to loosen'. So literally, 'relaxare' meant 'to loosen intensely' or 'to loosen again'.

Some simpler related Spanish words include 'relajar' (to relax), 'relajado' (relaxed), and 'relajo' (relaxation, mess). These all share the same Latin root 'relaxare' and maintain similar meanings related to loosening or becoming less tense. The word 'laxo' (loose, slack) is also related, coming directly from Latin 'laxus'.

Several common English words are related to 'relajadamente' through the shared Latin ancestor 'relaxare'. The most obvious is 'relax', which maintains almost the same meaning. Other related words include 'relaxation', 'relaxed', and 'lax'. The word 'lax' comes from Latin 'laxus' and maintains the original meaning of 'loose' or 'not strict', while 'relax' developed from the intensified form with 're-' prefix.